She can keep her money separate from his till he gets his money situation straightened out. Separate bank accounts, at least.
And you can keep your nose out of your "adult child's" business.
I am not a legal expert, but I WISH I knew some stuff before I got married 5 years ago (blended marriage) so while keeping her nose out of her adult child's business, there are some things that should be done. Yes, keep everything separate, but:
1. make sure both, BOTH have a credit report done on them before any vows and each is privy to see the others.
2. Pre-nup, pre-nup, pre-nup - including retirement funds & pets
Love does NOT replace trust.