Bitter baby mommas

Okay so question for those co parenting or step moms.

My boyfriend has a kid with another girl who absolutely hates me. She is insisting that I will hurt her child. ( never in a million years would I hurt a baby or child) That being said she refuses to let him see his daughter whether I’m around or not. She wont let his mom see her either. Any ideas on how to go about this? I’ve never been mean to her and I don’t even know her.

Also would it be rude of me to get my step daughter a Christmas gift and drop it off to her?