Perhaps we "buy" the house from them for the $328K balance to satisfy the lender and don't need a large down payment and then have a separate contract with them to pay $x per month until we've paid the full $172K amount.

Since it’s a new build, I was able to negotiate some great perks, like a 5.875% interest rate, no closing costs, a fridge, blinds, and even a backyard firepit.Pros:Good school districtLow interest rateMinimal CapEx and repairs (because it’s a new build)Low insuranceHigh-quality tenants (due to the school district and being a new build)Cons:Lots of new builds in the area, which could drive down prices and increase vacanciesThe Numbers:Price: $290KInterest Rate: 5.875%Down Payment: 25%Monthly Mortgage + Insurance + Taxes + HOA: $1,480 (I got really low insurance since it’s a new build and Alabama’s property taxes are low)Property Management: 10%Rent: $1,800 (this is under market because I wanted to rent it quickly—most units in the area were sitting vacant for 100+ days.

I have the opportunity to help a family member be part of a joint venture with them putting the down payment down.  

The payments and interest are high.

Here is the Collin Hays method of buying the property at what you want to pay:Don’t ask the seller what their best offer is.

Here are some tips to keep your projects moving smoothly and scale up:Managing ContractorsControl Payments: Break the rehab into phases and pay contractors as they complete each phase.

Or a seller finance calculator showing the monthly payment based on negotiated price, interest rate, down payment, etc.

Rent to Retirment (RTR) has very recently announced the RTR academy that investors can join for a one time payment to learn everything about investing.

They are able to See a COC return within weeks of the down payment, when the unit rents. 

As long as the rents can cover both the current PITI and proposed P&I payment, credit is at least 680. you should be able to qualify.