Im amid the pre-qualification process at a local bank, and heard back that the lowest down payment they offer for a primary residence loan on a small multi-family property is 15%.

You do this by showing a hardship that is not self-created. 

Start by reading the Ultimate Real Estate Investing Guide: https://www.biggerpockets.com/guides/ultimate-real-estate-investing-guide/introduction2.

Originally posted by @Eric Garces:How are you everyone, I am young and new to real estate.

Based on the scenario, I would start by researching construction loan options.

If he agrees to let the other person move in, make sure you put that in writing and have it signed by all parties.

A common issue is supply and demand effected by population changes, construction, economic issues, the job market and location.Personally I haven't seen vacancy issues at this time,  but I have gone through cycles of vacancy issues.

I would start by going right to this guy and ask for him to pay what I can justify for the cost of this issue to me.

It offers immediate cash flow and diversification across different real estate classes and markets, freeing you from the headaches of active management.

Then you can read a more in-depth book like The Book On Rental Property Investing by Brandon Turner or The Unofficial Guide to Real Estate Investing by Spencer Strauss.2.