If I want to start a new chat with 20 people, I have to enter all 20. It would be really nice to be able to grab a chat that has 17 of those people and use it as a template for a new chat and just add the missing 3. Or, find the that has those 20 plus a couple of more and use that as a template to remove the extras.

The chat history doesn't need to be preserved, just the list of recipients.