He rented his house out (dsd lived with her bf and child). DSD always made it clear his house was her inheritance and she wouldn't consider sharing it, fair enough. DH house turned into a money pit and so he sold it, not making much, he did put money into the business as have I.
Did your DSD and her DP do any DIY or offer to repair/upgrade the house when living there, seems a bit drastic to give up a house that you know is secure long term.
Or did her DF evict her?
The business should be 50% to your DC and 50% to who ever your DH decides to leave his half to.
Its not up to you to fill her own mothers shoes and hand over your inheritance to her.
I'll also add, having started a business from scratch that sounds a bit like yours in its a non product making one, so once retired the business isn't a kind you can sell, to enjoy the fruits of your labour and the lunches out or whatever you decide to spend your earned money on, with your DH.
Edited to say...
I miss understood in thinking you/your DH were the business, if you understand, as in there's no business unless someone in the know can run it.
Does your DSD/her DP work in the business now?
If not if you leave your % of the business to her is it not best that she/her DP work in the business before you hand it over so they know what's needed once it becomes hers.