Family problems?

It sounds like Grandpa and Grandma should understand, times have changed and stop interfering . You have two parents as you stated, and I see no need for an apology. It was decision to use the name, do you plan on them making your decisions in the future?It certainly doesn't hurt to listen to others concerns, but they have no right to tell you what to do. Ultimately you will be making your own decisions, and I see no damage here. Good luck!