It's only been two weeks since his daughter passed away.  You could ask him to drop by the store on his way home from work to pick up X, Y, Z but any specific arrangement or timeline or request for cash would make you look like a monster no matter how diplomatically you put it.  You are in a no win position here.  It sucks but you have no choice but to hold off for a while.  Sorry. 

No rules or expectations set up before he moved in? I guess you and your DH will have to talk and come up with the list including a timeline. Have him pay rent even if it’s save to give back to him at the end of the term so he has enough for 1st months rent and a security deposit. 

Ugh, tough situation. Give it some time. Try Susanm's suggestion above to ask SS to bring home something you need while he's out.

In the meantime, think about how you'll negotiate this and what timeline and rules you want.

I think there will be a precise moment to bring it up -- when the grieving has subsided a little, but before SS gets too comfortable with obligation-free living. You'll have to figure out when that is.

Judging by what I read on this site, you'll have a fight no matter when you do this. But doing it too soon will convolute grief/insensitivity with a very real issue. So time it well.

If your guy has any sort of complaint or run in with SS anytime soon, that will be your time to raise it, but only to your guy. Let him do the heavy lifting of delivering the message to SS.

Remember, when you talk to your guy, be it sooner or later, try not to make it too much about yourself. That will make him defensive. Make it about what's best for your kids and your SS.

If he works fulltime and has resources, he could've found a place to rent instead of being a titty baby.

I have been very closely in  your shoes. My SS died in his 20's a couple years ago of  meningitis. A year later younger SS dropped out of college with one semester left due to depression, and I believe, some other psychological problems somewhat like Asbergers. Anyway, I had to be careful because we certainly didn't want to lose another child, yet for a year and a half SS lived with us with zero responsibilities. I mean sleep till 2 pm, wait for me to cook dinner then go back to his room and play video games all evening and all night! The depression and other problems didn't seem to be there after the first 6 months and getting him back on medication; but DH let him hang out another year with no financial responsibilities or contribution to the household chores. Not to mention finishing his degree.  Then after more than a year DH finally told him he wasn't being fair to me and he had to try to get a job! He did get a job and apartment but still hasn't gone back to school. This is sad because he is extremely smart and so close to graduating.  Believe me, I had a really hard time during this period. I was stuck given the situation of mental illness and loss of another child and I think you are too for awhile. Hopefully you won't be where I was. Definitely give them both some time though. It is so hard being the spouse of someone who has lost a child. You suffer in ways too because they suffer, but yours is silent. There is guilt too because you don't have the same emotional grief.  Siblings suffer more from the loss at that age than he may let on.Good luck to you. I'm here if you ever need to talk.

Time to give him a shopping list and a chore list. He is an adult and must ahve contributory responsibility in the home.

To cap that off... dump his two younger sibs in his lap and tell him that you and DH are going out for a date and he is responsible for his baby sibs until you and dad return.

He wants to crash in your marital home so he can be treated as both an adult and a child.  No quarter. He does as he is directed or he leaves.

My condolences to you and the family on the loss of your SD.

Good luck.