Possibly petty but all the same... At most of the children's parties we go to the parents keep the presents back in a pile for their DC to open later. Sometimes we get a nice note afterwards to say thank you but often we hear nothing at all. I'm not greatly inspired but I do try to pick things I think the child will like and tbh I feel sad to miss out on knowing if they liked it. Aibu to think you either open things then and there and say thanks, or you keep them back and write a note or mention it to say thanks later on?