That kind of thing :)In defense of the dumb, I have been saying we are in a bubble since 2009 but I have been blown by by many investors I think were less qualified bigger egos etc. 

This building should fall under that, but since the upstairs apartment is gutted, would this property still qualify? 

Some lenders will ask for a qualifying event like a marriage, divorce, or move to another location.

In that case you could live in one (assuming you qualify of course) using owner occupied financing on that particular property and investment financing on the other three. 

But we won’t qualify for a primary residence refi anymore, and I’ll need more equity to refinance as an investment property.Future investment goals: I want to own rental properties in the future, but I’m not sure if holding on to this one (which we already have) is the right move, or if it makes more sense to sell and build up savings for a better investment down the line.I’d really appreciate any advice on what I might be overlooking here.

I am sure there are qualified people to train you, but I would warn you to have anything Pace Morby or anyone else teaches reviewed by your attorney.  

If rent isn't paid following a 5 day grace period we post a late fee, followed by serving an Immediate Notice To Quit For Non-Payment, and then contacting our attorney to begin the eviction process.

Although, if they do not have stable income, based on our requirements (3x monthly rent) the sister alone would not qualify.

Alternatively, you could pursue a hard money loan for rental financing which wouldn't require certain rental income to qualify. 

They simply click the button to submit a general inquiry without knowing anything about the house, the location, or the qualifying criteria.