I would encourage you to start experimenting with tandem bikes. Have you gotten your daughter to ride a tandem or an afterburner/trailerbike?

Get the kids to be active rather than just riding in a trailer.

There are quite a few different designs and configurations for example the Kidz tandems are designed for kids on front.
Brown Cycles of Grand Junction, Colorado

There are also child stoker kits (stokid)
Precision Tandems - Pictures of you stokids!

And the weehoo trailer for the youngest kids, with the largest for kids up to 9.
Bicycle Trailers for Kids by Weehoo | Let the adventure begin - kids love it!

Tandems can be made for 2, 3, or 4, or perhaps even more riders. There are also side-by-side tandems (bike cars) generally not used for long-distance riding, but they could be fun nonetheless.

And, for an interesting "special needs" group, perhaps consider the Blind Stokers.
Welcome to the Blind Stokers Club Blind Stokers Club