You would not consider anyone a dependent for the purposes of the Homestead Credit who is not already a dependent on your return.
If you had someone other than your spouse living with you, only you can apply for the refund. Use the income of any other person living with you, except boarders, renters, your dependents, your parents, or your spouse’s parents.
http://www.revenue.state.mn.us/Forms_and_Instructions/m1pr_inst_16.pdf page 7
