They get a prescription for the service animal and then never go back to the doctor.4.

If they can prove they have used your land, had their fence there, etc. with no objections, then they may claim prescriptive easement. 

The agreement can be as simple as to say the 'property owner A' and property owner 'B' hereby acknowledge the proximity of their respective driveways and affirm that neither property has any easement right/necessity over the other.The concern here from a lender/title perspective is the ability to claim a prescriptive easement right.

You likely have a prescriptive easement for it since its been am open and notorious use for 30 years.

I have a feeling that it will be a prescription dated after the incident. 

I will request a doctor's note and/or prescription (and registration of ESA if available).

Worst case scenario is that they will gain a prescriptive easement to your property because you knew and neglected to do anything about it. 

@Tiffany Ralston - I use the marketplace and for silver level coverage (80% coinsurance and a doctor visit is like $25 with prescription coverage) it is $500 / mo just for meI don't have any pre-existing conditions and do not take regular medicationIf anyone has a better / cheaper solution I would be open to hearing it 

As to the Fund itself - Funds will self-certify, but, other than what is already prescribed by the format the Fund will take and how much money is raised - will have few other restrictions or prescriptions.  

You need to retain your attorney and understand prescriptive easements and adverse possession rights.