I think I have found out what colour Sonya is.
Wild bay with pangare!
She isn't a bay because she has black up to her fetlocks, then it is silver to her knee's/hocks. She has the pangare on her chest, belly, behind he elbow, and her throat.
I can't post pic because I'm not on my computer, but if you want to take a look just go to my horses.
I am going to get her tested as soon as I find the time too though, just t be sure! It has bugged me since I bought her.