@thumper1 : I believe some states may use the term more broadly than in the marital dissolution custodial/non-custodial parent context to refer to someone who is essentially a foster parent when, as might be the case here, legal guardianship remains with the state or county.
@thaovyvan : I do not know the answer to your question. It’s a toughie. Were your father’s parental rights officially/legally terminated? Are you an emancipated minor? There may be different words for these tings in your state. Do you have a college counselor in your school who can help? You might email the college board and see what response you get. Or, Google for children’s legal services in your area.