Addressing the invites help needed!

For a family? What if it's the couple and a kid?

Mr. & Mrs. John Doe and family?

The Doe Family?

What about where the wife kept her maiden name? And their kids?

Mr. John Doe, Mrs. Jane Smith, and family?

And what about my grandma and my aunt who go on the same invite? (My grandma cares for my aunt with Down's syndrome so they always go on the same invite).

Mrs. Jane Smith and Ms. Mary Smith?

AHHHH Why must I have such a complicated family?

i think in either case i would do The Doe Family. the only reason i wouldn't do the Doe Family is if you want to invite one kid and not the other.

eta: just saw your second quesiton. i'd do it as you have it put with grandma and aunt's name each listed. Also, it should be:

Mrs. Jane Smith
Ms. Mary Smith

no 'and'

Here is an article that can help you.
Addressing and Mailing Invitations