Mortgage and seller financing?

[Gavin Jex]

Hi, my grandparents want to sell me there home Michigan with a $70,000.00 HEL currently on the property. They would like me to finance the $70,000.00 into a conventional mortgage and also have them as a lien holder with a promissory note of $100,000.00 with $300.00 monthly payments with 0% interest until maturity. I don’t know if this is possible In the state of Michigan. Any guidance would be appreciated, the house is worth between $200,000 & $225,000 currently on the open market.