My question is why would you want to do that?? YG are in turmoil which is the reason so many groups are moving/have moved to groups.io.? Transfer your group to groups.io and the mothball the old YG by preventing anyone from posting except admins and put everyone on moderated status so if they try to post you can send them a message saying the YG is inactive and post to the new groups.io.? Keeping the old YG active defeats the whole purpose of moving to groups.io.
Bruce Wilson
Barrie, Ontario