Is this wrong?

My bf sister has 3 kids(ALL BOYS) ... We have 2 boys now pregnant with our first little girl.... We all excited but his grandma feels like she should do more for his sister kids than ours, she has never watch or kept our kids but she has the other boys 24/7... She always say it's "MY" FAULT I never brought them around when we stay like 5-10 mins away from each other... I tell my bf they not my family they yours.... And I really don't like how she can be so rude.. So said she don't get to be called a grandma to mines.. I really don't think I was wrong.. I always say if my granny was here my kids wouldn't have to worry about nothing