I'm sorry that you are dealing with this, Di. You have been through sooooo much already.
SSDI has a maximum family benefit that you can get based on all of your income. When I was collecting WC with my SSDI, my SSDI benefit (and my kid's benefits) was lower because the total income took me over whatever my cap was (they never told me a figure). My ssdi bumped up when WC payments ended. My kid's benefits jumped up huge after the change (from $66 each to $450 each)
Just report it to them. If you aren't receiving children's benefits, your new total might not be over your 'cap' income.
If you get a lump settlement for medical that documentation should be clear that it is for medical, NOT a lump sum salary payout. Are you working with a WC lawyer ?