diff --git a/app/views/france_connect/particulier/_password_confirmation.html.haml b/app/views/france_connect/particulier/_password_confirmation.html.haml
index c83addb8c..0bc209dff 100644
--- a/app/views/france_connect/particulier/_password_confirmation.html.haml
+++ b/app/views/france_connect/particulier/_password_confirmation.html.haml
@@ -7,6 +7,6 @@
   = hidden_field_tag :merge_token, merge_token
   = hidden_field_tag :email, email
   = label_tag :password, 'Mot de passe (8 caractères minimum)'
-  = password_field_tag :password, nil, autocomplete: 'current-password'
+  = password_field_tag :password, nil, autocomplete: 'current-password', id: 'password-for-another-account'
   = button_tag 'revenir en arrière', type: 'button', class: 'button secondary', onclick: 'DS.showNewAccount(event);'
   = submit_tag 'Fusionner les comptes', class: 'button primary'
diff --git a/app/views/france_connect/particulier/merge.html.haml b/app/views/france_connect/particulier/merge.html.haml
index f2acdb168..c8f4ae656 100644
--- a/app/views/france_connect/particulier/merge.html.haml
+++ b/app/views/france_connect/particulier/merge.html.haml
@@ -15,11 +15,11 @@
     %label Ce compte #{@fci.email_france_connect} vous appartient-il ?
     %fieldset.radios
       %label{ onclick: "DS.showFusion(event);" }
-        = radio_button_tag :value, true, false, autocomplete: "off"
+        = radio_button_tag :value, true, false, autocomplete: "off", id: 'it-is-mine'
         Oui
 
       %label{ onclick: "DS.showNewAccount(event);" }
-        = radio_button_tag :value, false, false, autocomplete: "off"
+        = radio_button_tag :value, false, false, autocomplete: "off", id: 'it-is-not-mine'
         Non
 
   .fusion.hidden
diff --git a/spec/features/france_connect/france_connect_particulier_spec.rb b/spec/features/france_connect/france_connect_particulier_spec.rb
index 6c5b98520..4498f8031 100644
--- a/spec/features/france_connect/france_connect_particulier_spec.rb
+++ b/spec/features/france_connect/france_connect_particulier_spec.rb
@@ -34,18 +34,67 @@ feature 'France Connect Particulier Connexion' do
           allow(FranceConnectService).to receive(:retrieve_user_informations_particulier).and_return(france_connect_information)
         end
 
-        context 'when is the first connexion' do
+        context 'when no user is linked' do
           let(:france_connect_information) { build(:france_connect_information, user_info) }
 
-          before { page.find('.france-connect-login-button').click }
+          context 'and no user has the same email' do
+            before { page.find('.france-connect-login-button').click }
 
-          scenario 'he is redirected to user dossiers page' do
-            expect(page).to have_content('Dossiers')
-            expect(User.find_by(email: email)).not_to be nil
+            scenario 'he is redirected to user dossiers page' do
+              expect(page).to have_content('Dossiers')
+              expect(User.find_by(email: email)).not_to be nil
+            end
+          end
+
+          context 'and an user exists with the same email' do
+            let!(:user) { create(:user, email: email, password: 'my-s3cure-p4ssword') }
+
+            before do
+              page.find('.france-connect-login-button').click
+            end
+
+            scenario 'he is redirected to the merge page' do
+              expect(page).to have_content('Fusion des comptes')
+            end
+
+            scenario 'it merges its account' do
+              page.find('#it-is-mine').click
+              fill_in 'password', with: 'my-s3cure-p4ssword'
+              click_on 'Fusionner les comptes'
+
+              expect(page).to have_content('Dossiers')
+            end
+
+            scenario 'it uses another email that belongs to nobody' do
+              page.find('#it-is-not-mine').click
+              fill_in 'email', with: 'new_email@a.com'
+              click_on 'Utiliser ce mail'
+
+              expect(page).to have_content('Dossiers')
+            end
+
+            context 'and the user wants an email that belongs to another account', js: true do
+              let!(:another_user) { create(:user, email: 'an_existing_email@a.com', password: 'my-s3cure-p4ssword') }
+
+              scenario 'it uses another email that belongs to another account' do
+                page.find('#it-is-not-mine').click
+                fill_in 'email', with: 'an_existing_email@a.com'
+                click_on 'Utiliser ce mail'
+
+                expect(page).to have_css('#password-for-another-account', visible: true)
+
+                within '.new-account-password-confirmation' do
+                  fill_in 'password', with: 'my-s3cure-p4ssword'
+                  click_on 'Fusionner les comptes'
+                end
+
+                expect(page).to have_content('Dossiers')
+              end
+            end
           end
         end
 
-        context 'when is not the first connexion' do
+        context 'when a user is linked' do
           let!(:france_connect_information) do
             create(:france_connect_information, :with_user, user_info.merge(created_at: Time.zone.parse('12/12/2012'), updated_at: Time.zone.parse('12/12/2012')))
           end