save the date question

Ok, I'm trying to get together an address list for the STD's. I searched this board and it seems like people send out one STD per household (even if there are adults who live with their parents and will get their own invitation).

My question is, in the case of adults who live with their parents do you address it to:

Mr. and Mrs. Smith and Family
or
The Smith Family.


And also, what about families that have children (who will not get their own invitation when the time comes)?

If everyone in the household is invited, I'd just put The Smith Family.

If there are some children invited (i.e. teenagers) and others not, (i.e. babies) I'd send separate STD's.