Sparks flying

Happily re-married now, my daughter and stepson are both home from uni.
The trouble is my stepson is bone-idle. He doesn't contribute anything to the home but lazes around all day playing videos or computer games. He never offers to cook, rarely does his laundry and makes a bad but rare job of wshing up. He ploughs through the food cupboard finding any food he doesn't need to cook to eat. He also has disgusting habits. My daughter is at her wits end with him. It's come to a head because he's eaten her gluten free ice creams. He claims he has no money but will leave the house to buy a Subway breakfast. All these things seem trivial, typical of a teenage student.
My daughter is a student too. She has no money during the summer and she gets upset that other people help themselves to the things she bought.
Yeah she has annoying habits too but she is 23.
My stepson says 'i was going to replace them but forgot' Pretty bad memory for someone doing a masters in genetics in September. He's 29! yes 29!
It's doing my fruit! Sorry guys i needed to vent off somewhere.

There's a person missing from your post - your new wife, his mother. What does she say/think about the situation? I note you are happily remarried and that's great news, but you need to sort out this problem and not allow this behaviour to spoil things.

Does he have a student loan and has it run out? Living at home might sound like a great idea when you're broke, but this situation is clearly not working. He may not have any money but he coould contribute to the household in other ways, like doing the washing up properly at the very least. He can't just expect to come home and behave like a teenager at 29 and it's inevitable there will be tension and rows.

Don't feel bad about setting boundaries in your pwn home. He's playing on your good nature treating the place like a free hotel.
It’s reasonable to expect grown-up kids to pull their weight around the house. He's not a child any more and needs to grow up with a bit of tough love from you and his mother.

Actually, I'm the wife sorry if I've confused in any way. The manboy is my husband's son. My husband admits that he's probably allowed him to rifle the cupboards when he was growing up but knows that he is bone idle. Manboy has pleny of money, something my daughter doesn't have. We don't expect housekeeping money from either of them while they are studying. They both have siblings that live away from home and run their own households but he seems to always have money in the bank (he paid his sister that lives away's credit card debt a few weeks ago) He is bone idle passive agressive. I do feel that he has walked all over his dad and the rest of us but his dad doesnt say much to keep the peace, well there isn't much of that going on at the moment.

Tell him to find somewhere else to live.

Did you discuss children staying over when you and your new partner got together?

They were already adults when we got together. My daughter is 23 and the manboy/stepson is 29!
He will be living somewhere else when he goes to do his masters degree in a few weeks. University holidays are too long.

In a few weeks he will be somewhere else is it worth causing upset over a short visit especially as it doesn't bother your husband. Concentrate on your stepson's good points he paid his sister's debt so obviously has a kind heart, he should pay your daughter to replace her missing groceries but it's not really any of her business if he has disgusting habits unless they directly affect her and in that case it's not your job to intervene between 2 adult visitors who I would expect to sort out their own differences.