You can register her as a pinto SOLELY based on her coloring without having any information on the parents at all. Its called hardship registering. I have a foal whos mom was a grade saddlebred and he was elidgable to be registered pinto because he is tobiano. Paints on the other hand have to have at LEAST one REGISTERED paint parent (reguardless of the pattern of said parent) and a parent that is either APHA, AQHA, or JC registered TB reguardless of parent color. Basically give up on APHA. It will not happen with this cross. Get her PtHA registered. There is actually a nice club that is kept up unlike most color registries.