diff --git a/app/models/concerns/dossier_champs_concern.rb b/app/models/concerns/dossier_champs_concern.rb
index 9bd0cbd5c..ab5a7545e 100644
--- a/app/models/concerns/dossier_champs_concern.rb
+++ b/app/models/concerns/dossier_champs_concern.rb
@@ -39,6 +39,46 @@ module DossierChampsConcern
     end
   end
 
+  def find_type_de_champ_by_stable_id(stable_id, scope = nil)
+    case scope
+    when :public
+      revision.types_de_champ.public_only
+    when :private
+      revision.types_de_champ.private_only
+    else
+      revision.types_de_champ
+    end.find_by!(stable_id:)
+  end
+
+  def champs_for_prefill(stable_ids)
+    revision
+      .types_de_champ
+      .filter { _1.stable_id.in?(stable_ids) }
+      .filter { !revision.child?(_1) }
+      .map { champ_for_update(_1, nil) }
+  end
+
+  def champ_for_update(type_de_champ, row_id)
+    champ, attributes = champ_with_attributes_for_update(type_de_champ, row_id)
+    champ.assign_attributes(attributes)
+    champ
+  end
+
+  def update_champs_attributes(attributes, scope)
+    # TODO: remove after one deploy
+    if attributes.present? && attributes.values.filter { _1.key?(:with_public_id) }.empty?
+      assign_attributes("champs_#{scope}_all_attributes".to_sym => attributes)
+      @champs_by_public_id = nil
+      return
+    end
+
+    champs_attributes = attributes.to_h.map do |public_id, attributes|
+      champ_attributes_by_public_id(public_id, attributes, scope)
+    end
+
+    assign_attributes(champs_attributes:)
+  end
+
   private
 
   def champs_by_public_id
@@ -53,4 +93,39 @@ module DossierChampsConcern
       champ
     end
   end
+
+  def champ_attributes_by_public_id(public_id, attributes, scope)
+    stable_id, row_id = public_id.split('-')
+    type_de_champ = find_type_de_champ_by_stable_id(stable_id, scope)
+    champ_with_attributes_for_update(type_de_champ, row_id).last.merge(attributes)
+  end
+
+  def champ_with_attributes_for_update(type_de_champ, row_id)
+    attributes = type_de_champ.params_for_champ
+    # TODO: Once we have the right index in place, we should change this to use `create_or_find_by` instead of `find_or_create_by`
+    champ = champs
+      .create_with(type_de_champ:, **attributes)
+      .find_or_create_by!(stable_id: type_de_champ.stable_id, row_id:)
+
+    attributes[:id] = champ.id
+
+    # Needed when a revision change the champ type in this case, we reset the champ data
+    if champ.type != attributes[:type]
+      attributes[:value] = nil
+      attributes[:value_json] = nil
+      attributes[:external_id] = nil
+      attributes[:data] = nil
+    end
+
+    parent = revision.parent_of(type_de_champ)
+    if parent.present?
+      attributes[:parent] = champs.find { _1.type_de_champ_id == parent.id }
+    else
+      attributes[:parent] = nil
+    end
+
+    @champs_by_public_id = nil
+
+    [champ, attributes]
+  end
 end
diff --git a/app/models/concerns/dossier_prefillable_concern.rb b/app/models/concerns/dossier_prefillable_concern.rb
index bbcfdc8e1..d0c21a2bf 100644
--- a/app/models/concerns/dossier_prefillable_concern.rb
+++ b/app/models/concerns/dossier_prefillable_concern.rb
@@ -13,8 +13,4 @@ module DossierPrefillableConcern
     assign_attributes(attributes)
     save(validate: false)
   end
-
-  def find_champs_by_stable_ids(stable_ids)
-    champs.joins(:type_de_champ).where(types_de_champ: { stable_id: stable_ids.compact.uniq })
-  end
 end
diff --git a/spec/models/concern/dossier_champs_concern_spec.rb b/spec/models/concern/dossier_champs_concern_spec.rb
new file mode 100644
index 000000000..f0d2a0357
--- /dev/null
+++ b/spec/models/concern/dossier_champs_concern_spec.rb
@@ -0,0 +1,294 @@
+RSpec.describe DossierChampsConcern do
+  let(:procedure) do
+    create(:procedure, types_de_champ_public:, types_de_champ_private:)
+  end
+  let(:types_de_champ_public) do
+    [
+      { type: :text, libelle: "Un champ text", stable_id: 99 },
+      { type: :text, libelle: "Un autre champ text", stable_id: 991 },
+      { type: :yes_no, libelle: "Un champ yes no", stable_id: 992 },
+      { type: :repetition, libelle: "Un champ répétable", stable_id: 993, mandatory: true, children: [{ type: :text, libelle: 'Nom', stable_id: 994 }] }
+    ]
+  end
+  let(:types_de_champ_private) do
+    [
+      { type: :text, libelle: "Une annotation", stable_id: 995 }
+    ]
+  end
+  let(:dossier) { create(:dossier, procedure:) }
+
+  describe "#find_type_de_champ_by_stable_id(public)" do
+    subject { dossier.find_type_de_champ_by_stable_id(992, :public) }
+
+    it { is_expected.to be_truthy }
+  end
+
+  describe "#find_type_de_champ_by_stable_id(private)" do
+    subject { dossier.find_type_de_champ_by_stable_id(995, :private) }
+
+    it { is_expected.to be_truthy }
+  end
+
+  describe "#project_champ" do
+    let(:type_de_champ_repetition) { dossier.find_type_de_champ_by_stable_id(993) }
+    let(:type_de_champ_public) { dossier.find_type_de_champ_by_stable_id(99) }
+    let(:type_de_champ_private) { dossier.find_type_de_champ_by_stable_id(995) }
+    let(:row_ids) { dossier.project_champ(type_de_champ_repetition, nil).row_ids }
+
+    context "public champ" do
+      let(:row_id) { nil }
+      subject { dossier.project_champ(type_de_champ_public, row_id) }
+
+      it { expect(subject.persisted?).to be_truthy }
+
+      context "in repetition" do
+        let(:type_de_champ_public) { dossier.find_type_de_champ_by_stable_id(994) }
+        let(:row_id) { row_ids.first }
+
+        it {
+          expect(subject.persisted?).to be_truthy
+          expect(subject.row_id).to eq(row_id)
+          expect(subject.parent_id).not_to be_nil
+        }
+      end
+
+      context "missing champ" do
+        before { dossier; Champs::TextChamp.destroy_all }
+
+        it {
+          expect(subject.new_record?).to be_truthy
+          expect(subject.is_a?(Champs::TextChamp)).to be_truthy
+        }
+
+        context "in repetition" do
+          let(:type_de_champ_public) { dossier.find_type_de_champ_by_stable_id(994) }
+          let(:row_id) { row_ids.first }
+
+          it {
+            expect(subject.new_record?).to be_truthy
+            expect(subject.is_a?(Champs::TextChamp)).to be_truthy
+            expect(subject.row_id).to eq(row_id)
+          }
+        end
+      end
+    end
+
+    context "private champ" do
+      subject { dossier.project_champ(type_de_champ_private, nil) }
+
+      it { expect(subject.persisted?).to be_truthy }
+
+      context "missing champ" do
+        before { dossier; Champs::TextChamp.destroy_all }
+
+        it {
+          expect(subject.new_record?).to be_truthy
+          expect(subject.is_a?(Champs::TextChamp)).to be_truthy
+        }
+      end
+    end
+  end
+
+  describe "#champs_for_export" do
+    subject { dossier.champs_for_export(dossier.revision.types_de_champ_public) }
+
+    it { expect(subject.size).to eq(4) }
+    it { expect(subject.first).to eq(["Un champ text", nil]) }
+  end
+
+  describe "#champs_for_prefill" do
+    subject { dossier.champs_for_prefill([991, 995]) }
+
+    it {
+      expect(subject.size).to eq(2)
+      expect(subject.map(&:libelle)).to eq(["Une annotation", "Un autre champ text"])
+      expect(subject.all?(&:persisted?)).to be_truthy
+    }
+
+    context "missing champ" do
+      before { dossier; Champs::TextChamp.destroy_all }
+
+      it {
+        expect(subject.size).to eq(2)
+        expect(subject.map(&:libelle)).to eq(["Une annotation", "Un autre champ text"])
+        expect(subject.all?(&:persisted?)).to be_truthy
+      }
+    end
+  end
+
+  describe "#champ_for_update" do
+    let(:type_de_champ_repetition) { dossier.find_type_de_champ_by_stable_id(993) }
+    let(:type_de_champ_public) { dossier.find_type_de_champ_by_stable_id(99) }
+    let(:type_de_champ_private) { dossier.find_type_de_champ_by_stable_id(995) }
+    let(:row_ids) { dossier.project_champ(type_de_champ_repetition, nil).row_ids }
+    let(:row_id) { nil }
+
+    context "public champ" do
+      subject { dossier.champ_for_update(type_de_champ_public, row_id) }
+
+      it {
+        expect(subject.persisted?).to be_truthy
+        expect(subject.row_id).to eq(row_id)
+      }
+
+      context "in repetition" do
+        let(:type_de_champ_public) { dossier.find_type_de_champ_by_stable_id(994) }
+        let(:row_id) { row_ids.first }
+
+        it {
+          expect(subject.persisted?).to be_truthy
+          expect(subject.row_id).to eq(row_id)
+          expect(subject.parent_id).not_to be_nil
+        }
+      end
+
+      context "missing champ" do
+        before { dossier; Champs::TextChamp.destroy_all }
+
+        it {
+          expect(subject.persisted?).to be_truthy
+          expect(subject.is_a?(Champs::TextChamp)).to be_truthy
+        }
+
+        context "in repetition" do
+          let(:type_de_champ_public) { dossier.find_type_de_champ_by_stable_id(994) }
+          let(:row_id) { row_ids.first }
+
+          it {
+            expect(subject.persisted?).to be_truthy
+            expect(subject.is_a?(Champs::TextChamp)).to be_truthy
+            expect(subject.row_id).to eq(row_id)
+            expect(subject.parent_id).not_to be_nil
+          }
+        end
+      end
+    end
+
+    context "private champ" do
+      subject { dossier.champ_for_update(type_de_champ_private, row_id) }
+
+      it {
+        expect(subject.persisted?).to be_truthy
+        expect(subject.row_id).to eq(row_id)
+      }
+    end
+  end
+
+  describe "#update_champs_attributes(public)" do
+    let(:type_de_champ_repetition) { dossier.find_type_de_champ_by_stable_id(993) }
+    let(:row_ids) { dossier.project_champ(type_de_champ_repetition, nil).row_ids }
+    let(:row_id) { row_ids.first }
+
+    let(:attributes) do
+      {
+        "99" => { value: "Hello", with_public_id: true },
+        "991" => { value: "World", with_public_id: true },
+        "994-#{row_id}" => { value: "Greer", with_public_id: true }
+      }
+    end
+
+    let(:champ_99) { dossier.project_champ(dossier.find_type_de_champ_by_stable_id(99), nil) }
+    let(:champ_991) { dossier.project_champ(dossier.find_type_de_champ_by_stable_id(991), nil) }
+    let(:champ_994) { dossier.project_champ(dossier.find_type_de_champ_by_stable_id(994), row_id) }
+
+    subject { dossier.update_champs_attributes(attributes, :public) }
+
+    it {
+      subject
+      expect(dossier.champs.any?(&:changed_for_autosave?)).to be_truthy
+      expect(champ_99.changed?).to be_truthy
+      expect(champ_991.changed?).to be_truthy
+      expect(champ_994.changed?).to be_truthy
+      expect(champ_99.value).to eq("Hello")
+      expect(champ_991.value).to eq("World")
+      expect(champ_994.value).to eq("Greer")
+    }
+
+    context "missing champs" do
+      before { dossier; Champs::TextChamp.destroy_all; }
+
+      it {
+        subject
+        expect(dossier.champs.any?(&:changed_for_autosave?)).to be_truthy
+        expect(champ_99.changed?).to be_truthy
+        expect(champ_991.changed?).to be_truthy
+        expect(champ_994.changed?).to be_truthy
+        expect(champ_99.value).to eq("Hello")
+        expect(champ_991.value).to eq("World")
+        expect(champ_994.value).to eq("Greer")
+      }
+    end
+
+    context 'legacy attributes' do
+      let(:attributes) do
+        {
+          champ_99.id => { value: "Hello", id: champ_99.id },
+          champ_991.id => { value: "World", id: champ_991.id },
+          champ_994.id => { value: "Greer", id: champ_994.id }
+        }
+      end
+
+      let(:champ_99_updated) { dossier.project_champ(dossier.find_type_de_champ_by_stable_id(99), nil) }
+      let(:champ_991_updated) { dossier.project_champ(dossier.find_type_de_champ_by_stable_id(991), nil) }
+      let(:champ_994_updated) { dossier.project_champ(dossier.find_type_de_champ_by_stable_id(994), row_id) }
+
+      it {
+        subject
+        expect(dossier.champs_public_all.any?(&:changed_for_autosave?)).to be_truthy
+        dossier.save
+        dossier.reload
+        expect(champ_99_updated.value).to eq("Hello")
+        expect(champ_991_updated.value).to eq("World")
+        expect(champ_994_updated.value).to eq("Greer")
+      }
+    end
+  end
+
+  describe "#update_champs_attributes(private)" do
+    let(:attributes) do
+      {
+        "995" => { value: "Hello", with_public_id: true }
+      }
+    end
+
+    let(:annotation_995) { dossier.project_champ(dossier.find_type_de_champ_by_stable_id(995), nil) }
+
+    subject { dossier.update_champs_attributes(attributes, :private) }
+
+    it {
+      subject
+      expect(dossier.champs.any?(&:changed_for_autosave?)).to be_truthy
+      expect(annotation_995.changed?).to be_truthy
+      expect(annotation_995.value).to eq("Hello")
+    }
+
+    context "missing champs" do
+      before { dossier; Champs::TextChamp.destroy_all; }
+
+      it {
+        subject
+        expect(dossier.champs.any?(&:changed_for_autosave?)).to be_truthy
+        expect(annotation_995.changed?).to be_truthy
+        expect(annotation_995.value).to eq("Hello")
+      }
+    end
+
+    context 'legacy attributes' do
+      let(:attributes) do
+        {
+          annotation_995.id => { value: "Hello", id: annotation_995.id }
+        }
+      end
+
+      let(:annotation_995_updated) { dossier.project_champ(dossier.find_type_de_champ_by_stable_id(995), nil) }
+
+      it {
+        subject
+        expect(dossier.champs_private_all.any?(&:changed_for_autosave?)).to be_truthy
+        dossier.save
+        dossier.reload
+        expect(annotation_995_updated.value).to eq("Hello")
+      }
+    end
+  end
+end
diff --git a/spec/models/dossier_spec.rb b/spec/models/dossier_spec.rb
index 8a05debe4..f1fbe3ab5 100644
--- a/spec/models/dossier_spec.rb
+++ b/spec/models/dossier_spec.rb
@@ -2183,41 +2183,6 @@ describe Dossier, type: :model do
     end
   end
 
-  describe '#find_champs_by_stable_ids' do
-    let(:procedure) { create(:procedure, :published) }
-    let(:dossier) { create(:dossier, :brouillon, procedure: procedure) }
-
-    subject { dossier.find_champs_by_stable_ids(stable_ids) }
-
-    context 'when stable_ids is empty' do
-      let(:stable_ids) { [] }
-
-      it { expect(subject).to match([]) }
-    end
-
-    context 'when stable_ids contains nil or blank values' do
-      let(:stable_ids) { [nil, ""] }
-
-      it { expect(subject).to match([]) }
-    end
-
-    context 'when stable_ids contains present values' do
-      context 'when the dossier has no champ with the given stable ids' do
-        let(:stable_ids) { ['My Neighbor Totoro', 'Miyazaki'] }
-
-        it { expect(subject).to match([]) }
-      end
-
-      context 'when the dossier has champs with the given stable ids' do
-        let!(:type_de_champ_1) { create(:type_de_champ_text, procedure: procedure) }
-        let!(:type_de_champ_2) { create(:type_de_champ_textarea, procedure: procedure) }
-        let(:stable_ids) { [type_de_champ_1.stable_id, type_de_champ_2.stable_id] }
-
-        it { expect(subject).to match_array(dossier.champs_public.joins(:type_de_champ).where(types_de_champ: { stable_id: stable_ids })) }
-      end
-    end
-  end
-
   describe 'BatchOperation' do
     subject { build(:dossier) }
     it { is_expected.to belong_to(:batch_operation).optional }