If you aren’t sure discuss it with your guidance counselor. My kids have answered various ways on different things but mostly have used the race which is the slight majority of their ancestors. We have a pretty large percentage of a second race but at various times in their lives my kids have felt it more or less I guess. The counselor said they could ethically put either, both, or one based on a listing of relatives and backgrounds. What I find interesting though is that friends of ours are on the Indian registry and they have a teeny tiny percentage of that ancestry but since it is specifically legally documented they never think twice about including it. We aren’t applying for any scholarships based on either ethnicity though as I think most of those you need 50% and we aren’t that high. Honestly though nowadays it seems like almost everyone has some type of mixture (at least where we live) and I wonder how much longer they will even care about these questions.