We're at the point where we're sending out thank you's, and this is the issue we've come up against. A lot of 18+ people are living with their parents, so they obviously got a separate invitation because they're 18+. Come the wedding, some of them were included in a joint gift/card with their parents (card read from: Mary, Bob, and adult child). So these adult children get their own thank you card even though they did not give their own card?