You or your cpa have to come up with a reasonable, defensible, percentage that is your primary verses the other two units.  

Would I charge them rent based upon an interest percentage of the $150,000?

Is it based on our percentage we own?

I have researched different aspects of particular zip codes such as what percentage of residents are renters in the neighborhood, how much is the average rent in a particular zip code (rent-o-meter and City of Minneapolis website), the price of homes that sold in April (Zillow) and interest rates. 

The extra percentage point on your loan is irrelevant if your property cash flows.

While I agree with the intent, I think they should be a percentage of the remaining balance and not necessarily the entire remaining balance.So who would do M2M? 

And do you recall any of the numbers in terms of the return percentage and how long that took to achieve?

@Charlie MacPherson I’m not actually selling real estate.Im connecting the buyer/seller for a percentage so therefore I’m not getting paid to sale the property.Im getting paid to advise someone on a great deal.

You should also consider that a lender will only give you a loan that is worth a percentage of the property and second mortgages carry high interest rates and even higher ones for second mortgages on investment properties, and if you will be able to make these payments each month.

Equal percentage of all profits?