Hello ladies

I need advice how to deal with the situation.

My mother in law takes my child over for sleepover almost every weekend and recently I found out they go to my sister in law house every Sunday. It’s not that we don’t get along, we don’t have much in common, and I don’t like that because me mil wants to spend time with her daughter she takes my kids there.

Go for a visit alone, not freaking every weekend. She kinda want to substitute my kids as if they are her daughter’s. And happy family spend all time together where I’m not even invited.

My husband doesn’t see a problem and thinks I’m silly for even talking about it as my mil helps us a lot!!

Ladies, please help me to find why it upsets me so much and how I can change it.

Thank you!!