Yay for Posie and her amazing kids! I agree that it sounds very hopeful.
A first Al-Anon or Alateen meeting is a lot to deal with. Not only were they meeting a new group, but a new group that meets solely to discuss and support members dealing with an extremely difficult subject. IMO, it was really great of you to allow them time to process it and to think of a time that you could be available to talk with them individually if they'd like to.
Sending lots of hugs and wishes for strength and peace to you and your family.