I'm not going to invite in-laws to my daughter's birthday
Why would you not want to invite your in-laws to your daughters birthday party?
I don't think they are useful for my child.
People shouldn't treat other based on whether they are useful or not. The in-laws are family and it would be good to invite them. Its not right to exclude family from your daughter's life.
I'm not going to associate with useless people
You should try to not view your in-laws as useless. No person is useless as everyone has unique qualities that make them who they are. In addition to that, your child really should know their grandparents.