Hi, y'all, I'm new. (My very first post!)
So, about convincing parents...
Mine began to be more considerate about actually getting a GP when I stopped squeaking at odd moments (not like I do that now) "Can i have a guinea pig?!!" lol
I finally got one when a friend of mine moved out of town.
Unfortunately, I only had him for a week and two days before he passed away, as, though I was taking very good care of him, the former owners didn't really, keeping him in a tiny cage for most of his dull, drear life of three years.
They now are going to let me get a pair of boys (I hope--it seems likely...) from a rescue place about an hour away. My parents now are okay with having GPs, and
--GUESS WHAT!--my mom has joined my enthusiasim, and especially likes long-haired ones.
So, maybe you could try getting your parents to get to know your piggie...
(Sorry about the long post...I felt like talking.)