The fact they are being difficult, and refusing the cash to give place back would have me concern and go on defense to do everything by the book on this one.

I was out at a conference last week.

I left there to start a new life and career in Las Vegas because it only made sense to me to move to the place that everyone goes to train or attend conferences.

shortly after shoot them a text letting them know you just emailed them and would like to set up a phone conference.

Then finally Clayton Morris himself showed in after many attemts to call him and he wanted a conference call with me.

@Noah Pruett most go to local real estate investing meet-ups or conferences.

@Ryan Blake Just google " uber air taxi" or "from drones to autonomous cars and flying taxis, TechCrunch's Tel Aviv 2018 conference had it all" or "Uber just unveiled a prototype of its futuristic air taxi" all interesting articles with time frame for deployment btw 2020 and 2023. 

Keep plenty of cash (or highly liquid, safe securities) reserves - I keep a minimum of $50k for my 10 units.Your cash flow is first line of defense.

In the plumber's defense, it could well be the foundation for this addition was not done properly. 

But there could always be specific circumstances where a shorter (or longer) hold period are appropriate.In your case an unsolicited offer to buy at an advantageous price would certainly provide a great defense if ever questioned.