I've dealt with a similar situation.  

This kind of language appears in commercial mortgages from time to time depending on the situation. 

I watch the market and know that she will never find another place to rent less the $625/month that allows animals in the area.I am looking for thoughts/advice on what others would do in this situation.

@Benjamin Black In this situation I recommend getting a home equity line of credit.

Reason being if deal goes bad you walk away clean and they suffer.I also would never recommend to anyone to have 100% leverage as your playing with fire in those situations. 

I had a similar situation with a duplex I recently bought, which was also my first investment property. 

Nobody can tell you what to pick - there's no "right" way, just the right strategy that fits with your situation and goals.

For some tax related situation he does not want to close this year.

LabelingAs part of your preparation process, consider and write down a summary of the situation as you know it.

My target area clearly has 20% duplexes, which were originally sfh.Then you get into situations where individual units aren't mirrored.