Are you sure that only the fast pass attractions have rider swap or whatever its called? I ask because my son is tall and 8 years old. But he has a heart defect and cant ride all the rides. When we go to
Disneyland we have been able to do this. Like the Matterhorn has no fast pass and we can still rider swap. We are making our first trip to the World next winter.
Well, it depends what YOU mean by "rider swap". A lot of people interchange Rider Swap, Child Swap, Baby Swap, and Rider Switch freely, while generally referring to Rider Switch passes.
You can't use the Fastpass line if there isn't one. So getting a pass that gives you access to a Fastpass line that doesn't exist isn't very helpful.
Some CMs can be liberal with giving out the RS passes, but the policy is its a height limit and that's it.
There are other possible ways to do old-fashioned "child swaps", but how they are handled, if they are even possible, depends on the attraction. Most attractions at WDW do not load and unload in the same area like at a lot of amusement parks, so you can't wait with a child at the loading area for the other adult to return to take the child while you then get on.
You can always speak with the CM what the possibilities are for a particular attraction. I've never had to do it so I'm not sure how they are handled at the different attractions.
I believe that at Tower of Terror, the option is for one adult and the child to use the "chicken exit", which is the central REAL elevator. This takes you up to the exit corridor, near the photo booth. You wait there for the first adult to return, and then you can go back down the elevator to the loading area.
I don't know if in your situation a Guest Assistance Card can be obtained, possibly with a doctor's note. Asking over in the
disABILITIES! forum might net you an answer on that. I understand these cards are simply an indication to the CMs that extra accomodation may be necessary. Even if he couldn't qualify for a GAC, I'm sure they can make many recommendations.