If he seems desperate and also on medication due to pain, you may run into scheduling issues in the future based on his health.

I answer a lot of questions related to commercial on this site.

Sounds like you may have found a Gem among the rubble. one point of Info: In Texas most Title Companies will not recognize a "Quit Claim" Deed, except on occasion from one relative to another. 

She's been dealing with various health issues that have made paying rent on time a problem.

My fundamental thought with this thread is relates to we seem so driven by the data, numbers, deal, we forget to stop and learn from the people. 

There are two exceptions: Nonqualified use does not include any period of such use that occurs :(1) any time during the five-year period ending on the date of sale that occurs after the last day of use as a principal residence, or [ Meaning, of last  5 years, if you  rented a property of last 3 years does not trigger non qualified use, but in the last 5 years, if you first rent for 3 years and then move in for two years as a primary residence, 2/ 5 years is non qualified.](2) any time (up to two years) that the taxpayer is temporarily absent due to change in place of employment, health, or unforeseen circumstances. 

FL Triple R (relic residential relator), Commercial Realtors are generally very good negotiators and display a lot more common sense throughout deals.

I'm all about leaving lots of cushion as a sort of insurance to make sure I keep myself relatively secure so I'll keep in mind possibly raising those percentages a bit.

So start With Foster's work (No relation) "Tax free Exchanges Under sec 1031". 

But, if a slightly different, even related problem happens even the next day.