diff --git a/app/mailers/merge_completion_mailer.rb b/app/mailers/merge_completion_mailer.rb
index a5de27d72..29cacad5f 100644
--- a/app/mailers/merge_completion_mailer.rb
+++ b/app/mailers/merge_completion_mailer.rb
@@ -1,6 +1,6 @@
 class MergeCompletionMailer < NotifyMailer
   MERGE_COMPLETION_MERGING_ORGANISATION_TEMPLATE_ID = "b3b62e72-5ced-4515-8720-08bdc7bac792".freeze
-  MERGE_COMPLETION_ABSORBING_ORGANISATION_TEMPLATE_ID = "xxx".freeze
+  MERGE_COMPLETION_ABSORBING_ORGANISATION_TEMPLATE_ID = "7cdfefac-84c3-4054-8bd9-63103b3847b6".freeze
 
   def send_merged_organisation_success_mail(email, merged_organisation_name, absorbing_organisation_name, merge_date)
     send_email(
@@ -15,15 +15,20 @@ class MergeCompletionMailer < NotifyMailer
     )
   end
 
-  def send_absorbing_organisation_success_mail(email, merged_organisation_name, absorbing_organisation_name, merge_date)
+  def send_absorbing_organisation_success_mail(email, merged_organisations, absorbing_organisation_name, merge_date)
+    organisation_count = merged_organisations.count.to_s + " organisation".pluralize(merged_organisations.count)
+    pluralised_organisation = merged_organisations.count > 1 ? "these organisations" : "this organisation"
+    merged_organisation_list = (merged_organisations.count > 1 ? "The organisations are " : "The organisation is ") + merged_organisations.to_sentence(last_word_connector: " and ")
+
     send_email(
       email,
       MERGE_COMPLETION_ABSORBING_ORGANISATION_TEMPLATE_ID,
       {
-        merged_organisation_name:,
+        organisation_count:,
+        merged_organisations: merged_organisation_list,
         absorbing_organisation_name:,
         merge_date: merge_date.to_formatted_s(:govuk_date),
-        email:,
+        pluralised_organisation:,
       },
     )
   end
diff --git a/app/services/merge/merge_organisations_service.rb b/app/services/merge/merge_organisations_service.rb
index 7bca9f6f0..1ab115914 100644
--- a/app/services/merge/merge_organisations_service.rb
+++ b/app/services/merge/merge_organisations_service.rb
@@ -158,7 +158,7 @@ private
       if merged_user.present?
         MergeCompletionMailer.send_merged_organisation_success_mail(merged_user[:email], merged_organisation, @absorbing_organisation.name, @merge_date).deliver_later
       else
-        MergeCompletionMailer.send_absorbing_organisation_success_mail(user.email, @merging_organisations.map(&:name).join(", "), @absorbing_organisation.name, @merge_date).deliver_later
+        MergeCompletionMailer.send_absorbing_organisation_success_mail(user.email, @merging_organisations.map(&:name), @absorbing_organisation.name, @merge_date).deliver_later
       end
     end
   end
diff --git a/spec/mailers/merge_completion_mailer_spec.rb b/spec/mailers/merge_completion_mailer_spec.rb
index fb3f81ebb..6dcec5f89 100644
--- a/spec/mailers/merge_completion_mailer_spec.rb
+++ b/spec/mailers/merge_completion_mailer_spec.rb
@@ -29,18 +29,34 @@ RSpec.describe MergeCompletionMailer do
   describe "#send_absorbing_organisation_success_mail" do
     let(:merge_date) { Time.zone.local(2023, 1, 1) }
 
-    it "sends a merge completion E-mail via notify" do
+    it "sends a merge completion E-mail via notify for a single merge" do
       expect(notify_client).to receive(:send_email).with(hash_including({
         template_id: MergeCompletionMailer::MERGE_COMPLETION_ABSORBING_ORGANISATION_TEMPLATE_ID,
         personalisation: hash_including({
-          merged_organisation_name: "merged organisation",
+          organisation_count: "1 organisation",
+          merged_organisations: "The organisation is merged organisation",
           absorbing_organisation_name: "absorbing organisation",
           merge_date: "1 January 2023",
-          email: "user@example.com",
+          pluralised_organisation: "this organisation",
+        }),
+      }))
+
+      described_class.new.send_absorbing_organisation_success_mail("user@example.com", ["merged organisation"], "absorbing organisation", merge_date)
+    end
+
+    it "sends a merge completion E-mail via notify for a multiple org merge" do
+      expect(notify_client).to receive(:send_email).with(hash_including({
+        template_id: MergeCompletionMailer::MERGE_COMPLETION_ABSORBING_ORGANISATION_TEMPLATE_ID,
+        personalisation: hash_including({
+          organisation_count: "2 organisations",
+          merged_organisations: "The organisations are merged organisation and other organisation",
+          absorbing_organisation_name: "absorbing organisation",
+          merge_date: "1 January 2023",
+          pluralised_organisation: "these organisations",
         }),
       }))
 
-      described_class.new.send_absorbing_organisation_success_mail("user@example.com", "merged organisation", "absorbing organisation", merge_date)
+      described_class.new.send_absorbing_organisation_success_mail("user@example.com", ["merged organisation", "other organisation"], "absorbing organisation", merge_date)
     end
   end
 end
diff --git a/spec/services/merge/merge_organisations_service_spec.rb b/spec/services/merge/merge_organisations_service_spec.rb
index aa813b5dc..80ded190b 100644
--- a/spec/services/merge/merge_organisations_service_spec.rb
+++ b/spec/services/merge/merge_organisations_service_spec.rb
@@ -849,11 +849,11 @@ RSpec.describe Merge::MergeOrganisationsService do
       end
 
       it "sends a merge completion E-mail to the original absorbing organisation users" do
-        expect(MergeCompletionMailer).to receive(:send_absorbing_organisation_success_mail).with(absorbing_organisation.data_protection_officers.first.email, "fake org", "absorbing org", Time.zone.today).once
-        expect(MergeCompletionMailer).to receive(:send_absorbing_organisation_success_mail).with(absorbing_organisation_user.email, "fake org", "absorbing org", Time.zone.today).once
+        expect(MergeCompletionMailer).to receive(:send_absorbing_organisation_success_mail).with(absorbing_organisation.data_protection_officers.first.email, ["fake org"], "absorbing org", Time.zone.today).once
+        expect(MergeCompletionMailer).to receive(:send_absorbing_organisation_success_mail).with(absorbing_organisation_user.email, ["fake org"], "absorbing org", Time.zone.today).once
 
-        expect(MergeCompletionMailer).not_to receive(:send_absorbing_organisation_success_mail).with(merging_organisation_user.email, "fake org", "absorbing org", Time.zone.today)
-        expect(MergeCompletionMailer).not_to receive(:send_absorbing_organisation_success_mail).with(merging_organisation.data_protection_officers.first.email, "fake org", "absorbing org", Time.zone.today)
+        expect(MergeCompletionMailer).not_to receive(:send_absorbing_organisation_success_mail).with(merging_organisation_user.email, ["fake org"], "absorbing org", Time.zone.today)
+        expect(MergeCompletionMailer).not_to receive(:send_absorbing_organisation_success_mail).with(merging_organisation.data_protection_officers.first.email, ["fake org"], "absorbing org", Time.zone.today)
 
         merge_organisations_service.call
       end
@@ -976,14 +976,14 @@ RSpec.describe Merge::MergeOrganisationsService do
         end
 
         it "sends a merge completion E-mail to the original absorbing organisation users" do
-          expect(MergeCompletionMailer).to receive(:send_absorbing_organisation_success_mail).with(absorbing_organisation.data_protection_officers.first.email, "fake org, second org", "absorbing org", Time.zone.today).once
-          expect(MergeCompletionMailer).to receive(:send_absorbing_organisation_success_mail).with(absorbing_organisation_user.email, "fake org, second org", "absorbing org", Time.zone.today).once
+          expect(MergeCompletionMailer).to receive(:send_absorbing_organisation_success_mail).with(absorbing_organisation.data_protection_officers.first.email, ["fake org", "second org"], "absorbing org", Time.zone.today).once
+          expect(MergeCompletionMailer).to receive(:send_absorbing_organisation_success_mail).with(absorbing_organisation_user.email, ["fake org", "second org"], "absorbing org", Time.zone.today).once
 
-          expect(MergeCompletionMailer).not_to receive(:send_absorbing_organisation_success_mail).with(merging_organisation_user.email, "fake org, second org", "absorbing org", Time.zone.today)
-          expect(MergeCompletionMailer).not_to receive(:send_absorbing_organisation_success_mail).with(merging_organisation.data_protection_officers.first.email, "fake org, second org", "absorbing org", Time.zone.today)
+          expect(MergeCompletionMailer).not_to receive(:send_absorbing_organisation_success_mail).with(merging_organisation_user.email, ["fake org", "second org"], "absorbing org", Time.zone.today)
+          expect(MergeCompletionMailer).not_to receive(:send_absorbing_organisation_success_mail).with(merging_organisation.data_protection_officers.first.email, ["fake org", "second org"], "absorbing org", Time.zone.today)
 
           merging_organisation_too.users.each do |user|
-            expect(MergeCompletionMailer).not_to receive(:send_absorbing_organisation_success_mail).with(user.email, "second org", "absorbing org", Time.zone.today)
+            expect(MergeCompletionMailer).not_to receive(:send_absorbing_organisation_success_mail).with(user.email, ["fake org", "second org"], "absorbing org", Time.zone.today)
           end
 
           merge_organisations_service.call