I say let the sd look after her own accommodation. If things go badly with a house you bought then you could well end up looking like the bad dude. You could well be subsidizing the sd as well.
It is not good business to deal at non arm's length with the SD. Having said that I am still paying for my married daughter's car insurance and some tuition. But for the latter I am not talking a lot of money.
I remember many years ago a good looking coworker said that anybody that marries her gets to take over her debts. I wondered what happened to her.....