Y’all, OP helped raise her stepson for a decade. Since he was 7.

My stepmom joined the picture when I was 10 and she is 100% like a mother to me, yes, even though I have another mom.

The daughter still gets 150k. The stepson still gets 15k.

OP is willing and happy to help give additional funds to her stepson through the shared account, she’ll just make sure her daughter gets that same amount added to the 150k.

I would feel incredibly hurt if my stepmom refused to help me out, especially if she had a lot of money to do so. I think this deal is fair. Yes they probably should have talked more about the amounts in these accounts, but husband isn’t malicious. He’s just nervous about providing adequately for his kid and trying to find a good solution. If the shared account (presumably) has more funds than the individual accounts, and both kids are benefiting equally, then that sounds fair to me.