Originally Posted by SamOF

I don't know the Air Carrier Access Act well, but I do know that it's generally similar to the ADA. And I can see barely any argument that reseating coach passengers (or downgrading free upgrades) to seat the passengers together wouldn't be a reasonable accommodation.

And you can't just say rebook them on the next flight if they can't sit apart—if they would be accommodated but for the covered disability, and could reasonably be accommodated with their disability, then that's that.

For the record, and this comes from someone who rarely agrees to swap seats on planes and gets very, very cranky about it: Anyone who refuses to sit in a middle seat to help the OP sit with her interpreter should be ashamed of themselves.