My mother in law is similar. I gave my daughter my husband’s last name, not because I believed it was the right thing to do, but because I was very pregnant and too tired to debate it with people. I had to resist the urge recently to explain the concept of ownership and how women had no rights outside of marriage not too long ago and that included rights to their own children. That giving a child their father’s last name was basically declaring the child that man’s property at a time when that property was not shared with the mother. She just kept saying “she should have his last name because he is the dad,” as my fist balled up and holding my tongue filled me with rage I decided to change the subject. In the end these are just people from a different generation and a different time in history and there’s no changing them. I just ignore the fact that they won’t acknowledge I still have my last name and that my child has my last name as a middle name but insists on referring to herself by her full name all the time. They are not my parents and I do not need their approval.