They are currently working long-hours and are never home very much - we don't know when they intend to retire and think that it may take a catastrophic event that forces them to stop working. 

If you have an active business you can setup a Solo 401k plan for it but those funds can not be used for your personal or business investments. 401k can make investments on it's own but all transactions must be 'arms length'.

After that you have to schedule with the Sherriff to force eviction, usually takes a week or so to get on their schedule. 

Should we rather look into a different type of real estate investing such as flips to take advantage of the forced appreciation?

I have had 3 slip and fall claims just this year where the tenant was at fault, but the insurance carrier was forced to pay. 

It's unsecured, non performing, not even an arms length transaction, to a weak borrower.

They are usually forced into newer complexes.

Doing it this way is the cheapest, safest, and the only real answer is going to come from the stepson doing the right thing or a judge forcing the stepson to doing the right thing.

In the rare instances when your tenants do cost you an unexpected arm-and-a-leg for a plumbing or sewer bill, you'll find that they generally don't have the money to reimburse you for the expense and it ends up costing you a turnover...You can absolutely amend your leases to require the tenants pay a percentage (in this case 1/4) of the utilities.

The current look back period for transfers that are not arms length is 5 years.