Reassign Activity Post to Group Feed for Admin/User Control

Activity Feed / Reassign an activity post as an group post. An Admin or the User itself should be able to edit his post on the main activity feed and be able to reassign this one to a group-feed which he is a member of. Why? Instead of posting their content in the group-feed they sometimes post it on the main activity feed. Afterwards they are only able to change the content or to make the post private. But they are not able to remove the post from the main activity feed and assign it to a group-feed. So the only way to fix is that or the admin deletes the post and the asks the user if he can post it in the correct group-feed.