Onions, what have you chosen if you don't mind me asking??
People really need to keep their opinions to themselves. Our children, our choices and they need to respect that and not think they should be finding alternatives to avoid using it. One day, that baby is going to be an adult and will the nickname Grandma gave him as a one week old going to be cute at 20?? I think not!!
My mother doesn't like my eldest son's name: Christopher Jayden. I asked her what she would call him and she told me it's not up to her but if that's what we want to call him that's our choice and she's respectful of that. We draw the line at him being called Chris - it's not happening. But she calls him CJ. Always has and that's okay. DS2, He's Brayden-Lee Elwynne. Brayden-Lee she doesn't mind, Elwynne (my Grandfather's name) she hates with a passion. Apparently she used to tell my grandfather his name was horrible too. Lol. But the toss up for his middle name was between my Grandfather's first name and her middle name (Frances) and she thought I was cruel to use her name so I didn't. Needless to say, she's always got something to say about it while my Grandmother is tickled pink. The little dude is Alexander Gabriel. Don't know her thoughts on that because I haven't asked. We have Kairi Nicole picked for a girl and she LIKES that. I don't get my mother. :/
Anyhow, people are going to feel the have the right to have their say and feel their choice should be worth considering. Stand your ground and tell them that you have chosen your child's name and that it is NOT up for discussion nor is a nickname going to replace your child's name because your family doesn't like it. I'd be telling them to bugger off and not come back until they have learnt some respect.