And some people, like user u/True_Dot5878, called out how unequal treatment of siblings gets exacerbated in families where one sibling has a child and the other doesn’t: “The only reason your family is viewing you as stubborn or the a**hole is because certain people are very, ‘I have a child, so I’m more important than you’ attitude.”
“I’m going to assume you’re also childless. Your family believes you should go along with it and rename your dog because, in their eyes, a dog doesn’t compare to a child. They probably also believe that you have all this available free time that your sister doesn’t have (because, in their eyes, childless people don’t have any value or concerns or stressors or a life!). Your sister knew your dog’s name was Charlie and probably had no discussion with you to see if you were willing to change the dog’s name. And now you’re being strong-armed in this situation and expected to just do what your sister wants because your parents probably feel that ‘you don’t understand what it is like to be a parent.’
I say keep the dog’s name. This is your sister’s problem. Tell her to give her kid a nickname or change it. She’s got time to do it on the birth certificate.”