Inherited Tenants with no rental/lease agreement

When my great grandparents passed more than 20 years ago, my grandmother made a verbal agreement with a couple, which provided that they could live in the house for $100/yr as long as they acted as caretakers for the house and 100 acres of land surrounding it.
She never collected the nominal rent and they did as they were asked. Now my grandmother has passed leaving the property to my mother and uncle who are fine with the arrangement since they both live out of state.

However now there are concerns:
1.The tenants who are now elderly themselves have other relatives and their friends living in the house.
2. The tenants have always allowed locals access to the property for hunting and fishing with the owners full knowledge. But now younger people are doing damage to the pastures with their vehicles and who knows what else.
3. In response to this, the tenants erected a fence with a locked gate without notifying the owners.
4. There is an additional parcel of land which the owners have allowed childhood friend and neighbor to use to harvest hay for his herd. It has now been brought to the owners attention that he is hunting on the land which although in a rural area is in the city limits and probably illegal.

Can we now have the tenants sign a rental agreement, with restrictions as to who lives in the house, land use, and no improvements without owner approval.

The issue of owner liability is the main concern regarding the unrestricted access to the property and the activities taking place.

Adverse possession is also a concern, although I do not think they could meet all the conditions.

How should we proceed? Can anyone direct me to the applicable Alabama code sections pertaining to these issues?

[OHlandlord]

Unfortunately, I cannot give you the state statutes which would cover this. A real estate attorney could tell you which statutes would cover this situation. I would have some agreement drawn up for the tenants personally. Something that states a specific rent level (you can keep it $100 per year if you wish), but spells out exact restrictions on the property management you want them to follow (no hunting, no ATV, off-roading, or dirtbike riding, no fences or permanent improvements without written permission, etc.). You also want to spell out what you expect and will allow them to do (grow & harvest hay, do minor landscaping, trim trees and bushes, do minor repairs to the house under $XXX, etc.). Make sure it spells out that this agreement only extends to the elderly couple (name them) and no heirs or others. I'd seek the advice and expertise of an experienced real estate attorney for this. You don't want to write something that would accidently have adverse effects. The small fee he would charge will be worth it to head off future trouble.