His dad was a cop who died. He gets sent to live with relatives after getting in trouble. The school he ends up at has the NIS program. The family he ends up with is a mom, dad and two girls.he quits smoking when he gets to the new place. Please help it's driving me mad.
Damn, I've read this one as the unique features in you description are the nis bit and smoking with the rest being too vague and can describe many other stories as this is a simple premise to work off of
If I'm not mistaken the mc was sent away by widow mom for his safety to I think aunts family.
I know there is a nis universe category here but that doesn't nessacerily narrow it down as not all authors correctly mark/tag/label their stories to be included in the list for those stories and I can't use advanced search features as a free user to help you find it.
Hope someone with a better memory can point you in the right direction.
a search for "smoking aunt naked in school" gives:
Jonathon And Jackie: Naked In School by Dark Vision