I am half Mexican, so my kids are 1/4. When a form asks if we are Caucasian (not of Hispanic origin) or (Hispanic origin) I answer truthfully, they are Caucasian but of Hispanic origin. Their grandmother is from Mexico. I think if you are truthful you’re good. When I was in college I received a couple of scholarships from the national Hispanic scholarship fund and those specified 2 grandparents of Hispanic origin.