Officially, my answer is "Ask them." Barbara-as-Oracle, for example, may not see herself as disabled simply because she's a chair-user, and Cassandra may not, either, despite her difficulties in communication in a form that we understand.

There's a lot of characerization and other things you can do with those differing perspectives - people who think of Barbara as disabled will change their behavior around her, possibly to their detriment or severe tongue-lashing from Barbara.

We can avoid erasing disability by treating it the way the characters want it to be treated. And by not making disabled characters into stereotypes that get Very Special Episodes.