I know. But my mum just dismissed the idea. "Just write the card, and keep the peace". Why? My older sister (the middle sibling) didn't want to sent a card, either. But, in the end, gave in too because our oldest sister wouldn't have been happy if we did otherwise, and probably not talk to us for a while.
Though, I really wish my oldest sister would stop mentioning her boyfriend's opinion or something he likes (be it a book, movie, or some musician or band) everytime we have a conversation ("Oh, he's thinks this... Or He likes that"). So what? Just because we have alot in common doesn't mean I will, or have to, like the guy. And I've made no secret about the fact that I find my oldest sister's boyfriend to be rather smug, condescending and full of himself. But if I told her that, she'd definitely not talk to me for awhile.
Sorry, I'm just rambling on now... Anyway, you get my point.