If there’s no exit clause I’d take this opportunity to add one.

Time is your most scarce resource.I absolutely agree with this.

The people the seller should have this discussion with is the title company and or legal counsel.  

My goal this year is to go from analysis paralysis to taking action.

Hope this helps, and good luck with your next deal!

Is this a tenant you no longer want because of his filing?  

And indeed they do this all the time.I would get your own accountant's temperature on this first.   

There may be a couple of houses on the block that do not have driveways so this may not be the only one.

This might only apply to RM1. 

It sounds like a single family house where you will be living in the house(personal use).Therefore, you may not be getting the tax benefits you think you are.Consult an accountant.I am not sure why your sister would agree to this as well, she is losing $170,000 in this transaction and she faces the possibility of you increasing her rent.You also have to charge market rent or close to market rent or it is all deemed personal use.