diff --git a/app/services/users/merge_and_archive.rb b/app/services/users/merge_and_archive.rb
index a8e165f495..ce426162e9 100644
--- a/app/services/users/merge_and_archive.rb
+++ b/app/services/users/merge_and_archive.rb
@@ -8,19 +8,25 @@ class MergeAndArchive
     attribute :user_to_merge
     attribute :user_to_keep
     attribute :set_uid, :boolean, default: false
+    attribute :logger, default: -> { Rails.logger }
     private :user_to_merge, :user_to_keep, :set_uid
 
     def call(dry_run: true)
+      logger.info "Dry Run" if dry_run
+
       ApplicationRecord.transaction do
         move_applications(from_user: user_to_merge, to_user: user_to_keep)
         move_participant_id_changes(from_user: user_to_merge, to_user: user_to_keep)
         user_to_keep.participant_id_changes.find_or_create_by!(from_participant_id: user_to_merge.ecf_id, to_participant_id: user_to_keep.ecf_id)
         uid_to_keep = user_to_merge.uid if user_to_merge.uid.present? && user_to_keep.uid.blank?
 
-        Rails.logger.info("Archiving user ID=#{user_to_merge.id}")
+        logger.info("Archiving user ID=#{user_to_merge.id}")
         Users::Archiver.new(user: user_to_merge.reload).archive!
 
-        user_to_keep.update!(uid: uid_to_keep) if uid_to_keep && set_uid
+        if uid_to_keep && set_uid
+          logger.info("Setting UID=#{uid_to_keep} on user ID=#{user_to_keep.id}")
+          user_to_keep.update!(uid: uid_to_keep)
+        end
 
         raise ActiveRecord::Rollback if dry_run
       end
@@ -30,12 +36,16 @@ def call(dry_run: true)
 
     def move_applications(from_user:, to_user:)
       from_user.applications.each do |application|
+        logger.info("Moving application ID=#{application.id} from user ID=#{from_user.id} to user ID=#{to_user.id}")
         application.update!(user: to_user)
       end
     end
 
     def move_participant_id_changes(from_user:, to_user:)
-      from_user.participant_id_changes.update!(user: to_user)
+      if from_user.participant_id_changes.any?
+        logger.info("Moving participant ID changes IDs=#{from_user.participant_id_changes.pluck(:id)} from user ID=#{from_user.id} to user ID=#{to_user.id}")
+        from_user.participant_id_changes.update!(user: to_user)
+      end
     end
   end
 end
diff --git a/lib/tasks/merge_user_into_another.rake b/lib/tasks/merge_user_into_another.rake
index a597cff0ec..9aedf0ead5 100644
--- a/lib/tasks/merge_user_into_another.rake
+++ b/lib/tasks/merge_user_into_another.rake
@@ -22,7 +22,5 @@ task :merge_user_into_another, %i[user_ecf_id_to_merge user_ecf_id_to_keep dry_r
     exit 1
   end
 
-  logger.info "Dry Run" if dry_run
-
-  Users::MergeAndArchive.new(user_to_merge:, user_to_keep:, set_uid: true).call(dry_run:)
+  Users::MergeAndArchive.new(user_to_merge:, user_to_keep:, set_uid: true, logger:).call(dry_run:)
 end
diff --git a/spec/lib/tasks/merge_user_into_another_spec.rb b/spec/lib/tasks/merge_user_into_another_spec.rb
index 73bde01e1e..2fa55cad83 100644
--- a/spec/lib/tasks/merge_user_into_another_spec.rb
+++ b/spec/lib/tasks/merge_user_into_another_spec.rb
@@ -8,7 +8,7 @@
   let(:user_to_keep) { create(:user) }
   let(:service_double) { instance_double(Users::MergeAndArchive) }
 
-  before { allow(Users::MergeAndArchive).to receive(:new).with(user_to_merge:, user_to_keep:, set_uid: true) { merge_and_archive_service } }
+  before { allow(Users::MergeAndArchive).to receive(:new).with(user_to_merge:, user_to_keep:, set_uid: true, logger: an_instance_of(Logger)) { merge_and_archive_service } }
   after { Rake::Task["merge_user_into_another"].reenable }
 
   subject(:run_task) { Rake::Task["merge_user_into_another"].invoke(user_to_merge.ecf_id, user_to_keep.ecf_id, dry_run) }