First time rentals are about 33% of my total rentals.  66% of my total rentals are repeat rentals.like all things successful you pull up your sleeves super size it and just beat the tar out of any competition.. nice work. you get rewarded for doing all those things.

It's a nice-to-have in my eyes.I think what's more important is ensuring that there are proper incentives that reward those who are materially participating in the deal.

All about risk and reward.

But I know it could be a great reward in the end. 

There are rewards and riches for creativity in life!

But with out risk, there is no reward. 

Is there is any legal way to reward their heirs so I can move forward on the sale? 

While you definitely want to reward good tenants, its your business and not keeping your rents at the level of the market, its money out of your pocket.

if you don't already, study up on the rewards programs of the various card issuers. 

Detroit can be a very rewarding market if done right!