AITAH for confronting my dad about picking favorites so obviously?

So I (14M) and my sister (12F) confronted our dad (40M) for clearly preferring his girlfriend's (34F) kids (9F) and (13M) for example whenever we get in his car (we go to his house every oher weekend) he tells us all the stuff he did with them and stuff and he only does what they ask for example my sister asked for cotton candy he said no one of his girlfriends kids asked and he agreed my sister said "can I do it first since I asked first" and he said "you didn't ask first" so we confronted him and he denied everything and called us dramatic and snowflakes. AITAH?