Structuring A Creative Deal, I have a quick question

[Amani Clarke]

Hey guys so I've been talking to an agent regarding an on market 4 unit property in Brooklyn. He told me that the seller is open to selling on terms/ creatives however there is a mortgage on it that apparently can't be assumed. They've owned the property for about 2 years so there's about $500k in equity which is what I offered as a down payment. Ultimately I need help structuring this because it cant be a regular sub 2 since the mortgage is not assumable and it cant be a regular seller finance since it's not owned free and clear. Any advice? I also have no idea how or where to get the paperwork from to set this up. As you guys can probably guess this will be my first creative deal.