Better to overestimate and out perform than underestimate and hit a brick wall.  

Basically, the Max amount purchase price, option fee, and the years to exercise the option?

Number one thing to find out though is how much rent would your parents charge, this is really an exercise in futility without verifying that right?

Start with a manual process, then automate parts, being sure to create a way to track the performance of each marketing piece.  

But if there are particular 5 caps that are under performing I would consider trading them for better assets.  

I use excel and consolidate all income and expenses for each property (I add my mortgage payments and other landlord expenses) and make sure that my cash accounts reconcile for all my holdings (if there is a problem I call the manager and we try and figure things out).I use this excel for two things: Tracking my properties performance - mainly cash flow, cash balance, NOI and just to make sure the PM is on top of everything.I use this to input the data into QuickBooks (I do this manually). 

This is a non-performing, unsecured note. 

This is a non-performing, unsecured note.

Never have the seller perform the repairs in escrow.

Also, a good PM is very aligned with your goals as their ability to operate profitably is very tied the the performance of the properties.