That's good actually then because if she's mixed it would reduce genetic risks from breeding with an overo, wouldn't it?
It certainly would. I'm going to find a picture of Mighty Bright or Mighty Brights Brother and will be right back. They were real close to looking paint.
If you think she has any overo blood and you want to breed her to an overo stallion, get her tested for the overo gene. A lethal white foal is a heartbreak.