I think it depends on how you want it pronounced. To me, Vivian is vi vee uhn, and Vivienne is Vi vee in or Vi vee ann, depending on the accent of who is saying it.
All are legit, so I would say go with your grandmothers' spellings.
I have seen some cases where parents have chosen to pass down ridiculous spellings in the name of family tradition, and I think this can be a hassle. Here, though, they are all authentic spellings.
Thank you for all of your comments and votes. Sofia is how my paternal grandmother spelled it and honestly, I love it that way myself. My other grandmother is Vivienne but I think that although beautiful, it's a bit long. We still have time to decide for sure, but thanks again for the suggestions!
Re: Name spelling
This. I wouldn't mess with family names.
I voted for the first choice, but I agree with PP
All are legit, so I would say go with your grandmothers' spellings.
I have seen some cases where parents have chosen to pass down ridiculous spellings in the name of family tradition, and I think this can be a hassle. Here, though, they are all authentic spellings.