So my mother in law hates me and my oldest (my daughter) because she existed before I met my husband. When going to their house I was not allowed inside until this last Christmas. Our second son (both boys are biologically his) We sent a message to his family letting them know he was born. My MIL posted it on Facebook (which is whatever until you read what she wrote) she said " another grandchild was born that makes 12th grandchildren + 1 step grandchild" I was horribly offended by this along with one of his sister's. She actually posted saying if she feels the need to call out my daughter as different then she should have only put 10 grand children +2 adopted grandchildren +1 step grandchild. My husband has told her they need to start treating my daughter just like they treat the boys or we will not be around. She was very upset saying we were hurting the kids by doing that.

Now my daughter's bio grandma and aunt (even though I never married her dad) treat all three the same. They are excited to meet their newest grandchild/nephew.

Is it wrong to exclude his parents from their lives if they refuse to treat them the same?

This is an example of the little things she does to make sure we know she doesn't accept our daughter as her family.