“Someone I know mentioned that her daughter-in-law calls her by her first name and it makes her uncomfortable!” - My DIL calls us by first name and it is absolutely fine with both of us. However, we would be absolutely fine with any of her choices. Many years ago when my S. got married, the DIL actually asked us and we told her that we do not have any preferences, not important. I also do not care what are other families’ practices, whatever suits them, I cannot be bothered by these, I just do not notice these things.
MichiganGeorgia, I am in my sixties and my siblings and I still refer to our parents as Mommy and Daddy when we speak about them. We called our mother Mommy until she died; though we refer to our father as Daddy, we call him Dad when we speak to him.