https://www.irs.gov/pub/irs-pdf/p537.pdf
Sale to a Related Person
"Selling your property to a related party can preclude you from utilizing an installment sale.
The IRS doesn’t allow special tax treatment if an installment sale is made to a related party."
질문자분의 케이스가 위 규정의 예외조항 충족 여부를 담당 CPA/EA와 상담하시기를 권합니다.