So when they got the disability payments originally, did those get included as income? 

If so, then you should be able to use Claim of Right for the repayment to the disability company since that money was already taxed. 

If not, I think they may be out of luck.

You've done the lump sum calculations, allocating the figures to the correct years (theres a smart worksheet for that) and it still makes too much taxable in 2022?