Your lender should use the f/f that can finance the property.  

Where is the property located.assuming the seller added the ADU and did not disclose the ADU in disclosure forms, you may have recourse (depending on the rules of your jurisdiction) but it may cost you some legal fees. 

I would do some online research into Realtors in your area to see if you can make a connection.As @Michael Dumler pointed out, wholesalers are going to be a more reliable source for consistent off-market properties with margin.

Awesome job with getting a cash flowing property!

Since acquiring a four-unit property on the Northwest side, my bi-monthly bill has typically been around $500.

If you're looking to save some time shifting through properties, our company, Winnow, automatically scans and analyzes every newly listed property and then sends you the ones with potential.

We have a mixed use apartment/commercial property for sale where the owner would entertain seller financing.

You have to be willing to sell your properties and access the equity to buy up. 

For example, I mention that every adult must pay a $30 application fee, pass my credit/criminal background, make a combined income of 3x the rent, and whether or not the property accepts pets.

Hi Shelby To determine rental prices and demand in a neighborhood, start by researching comparable rentals in the area, focusing on properties of similar size, type, and amenities.