H.,
Check out the local Garland Parks and Rec! http://www.ci.garland.tx.us/Home/Departments/Recreation+a...
They can help you find something for everyone.
My kids have similar age differences, and we do make the older ones sit out while the younger ones play and then the other way around. Even w/o the disabilities it isn't easy to find something for everyone.
As summer approaches you can also check out the web pages for the major theaters- last year 2 of them did free daily kid movies.
Maybe different vacation Bible Schools in your area- they are usually free.
Another option for YOU- check out the Friday NITE friends program at Custer Road Methodist church. The offer babysitting for speacial needs kids and their siblings! For more information, contact Judith Jolly at ext. 247, ____@____.com or visit www.fridaynitefriends.org.
Have a fun summer!
D.