In this situation, you use the PLUS MPN for Direct PLUS Loans which are available to parents of undergraduate students
What is contained within an MPN when applying for federal student aid?
The MPN includes the terms and conditions of the loan that you receive. You are entitled to receive more than one loan under an MPN over a period of 10 years, which can be used to pay for your or your child's educational costs. This is provided your school is authorized to use the MPN in this way. Your school will be able to inform you which loans, if any, you are eligible to receive