Welcome to the forum. Kinda a sad note to start out with here, but we all understand.
You can post it in the for sale section here on the forum. There is also a classified ad section that is free to post on
www.airstream.org and on airstream.net in their forum.
Hope that you are able to upgrade to somthing that will hold your newly expanded family and that it says Airstream on it!
BTW I may know of a 290 coming up for sale...........