What's the etiquette for sending thank you cards after an engagement party? A few of our guests brought gifts (mostly bottle of alcohol), but because we did an open house style party I didn't personally get to see who all brought what, and the gifts don't have their names on them. Do I need to send thank you cards to everyone? Or just people who brought gifts? And in that case how would I go about asking who brought which item without seeming rude?