How to handle property under contract where tenants leave

[Ryan Moore]

Purchased my first 4-plex earlier this year and while under contract, 2 of the 4 tenants just left, breaking their lease.  The owners at the time did not alert me to the change in occupancy and I had to find out about this change on my own thru random inspections of my own.

Going forward, with future deals where the units are occupied, what strategies should I utilize to help ensure that I'm not taken by surprise when tenants up and leave.  Should I have it built into the contract that the owners must alert me in X amount of days when a unit goes unoccupied?  Should I have something in the contract where I can back out of the deal upon leaning about a change in occupancy?