How to deal with people that come to your family meetings and you don't like them?

My Uncle just started dating a lady a few years ago. But the lady seems very selfish because when we had a family meeting over my uncle's house the lady just started putting the food away.Her daughter used to stare at me when we were at my family gatherings but she seems like she got a attitude problem.Last Week my Uncle asked her if my mom can drive with her and she said why..And plus it seems like my Uncle's girlfriend and her daughter are pretty rough and my uncle is not like that we have always had a peaceful and nice family. But i don't want them to bring any drama in my uncle's life or my family's life. We've always had a good nice family but they came in and messed everything up. It is really making me mad.We never go to none of their family stuff but they always coming to our family stuff.It seems like my Uncle is taking their family or our family and we been his family way before them.All they do when they come to my family gatherings is just sit there and stare like some wackos. family.And the thing that really upsets me is that they always coming to our family meeting.My Uncle's girlfriend is very selfish it's all about my uncle and her family.Their not my family. Why do they always come to our family gatherings they don't have to? My Only problem is he seems to be taking them over His family and family always comes first you never put a lady before your family.....i wish i never even met them..