Alright, so I've already finished addressing all of my invitations so it's a matter of knowing how badly I messed up.
I am not doing a return envelope for RSVP but included a card to tell the guests how to do RSVP paperless.
Because I can't address all of the guests including their children on the none-existent envelope I decided to put all of their names on the outer envelope:
Mr. & Mrs. Smith + Katty & Tom(kids names)
How badly did I mess up?