I like it, so much I'm doing almost exactly that with a partner. 

I want to purchase my second property within 4-6 months of moving into my multifamily house hack, but looking for a guidance on the strategy to do so.

So even though you do your due diligence you sometimes don't get what you're looking for.

Could not find much online so figured I would turn to BP.

@Angelica CristiIt has been a year or 2 since I last purchased on Auction.com so things could have changed.  

I started investing here in 2016 so it's been 8-9 years for me.

At that time we could renovate the ground floor apartment and potentially turn it into (2) apartments for a total of (5).My questions come down to how do we deal with the existing 40k mortgage, whether we can make it work so her parents aren't paying much in rent, if anything at all, and whether or not we set up any legal entity, like a trust to help the legal situation of paying off her sister down the road. 

So you pay for it with a credit card and when the bill comes you make the payment.

Look for some of those to go in as an LP (limited partner) and learn and grow your knowledge, skills and investment money so you'll be ready for the next accredited deal. 

So far, so good.