I agree with Black Sheep. I wouldn't give them a letter. Let them do what they want...like spit into the wind. They had NO power unless YOU give it to them. Hopefully the younger guy will let your info sound down and he will begin to think and reason. I just walked away,, I never sent a letter, I put a 6ft chain link fence around my property with a lock. My friends call it my "witness protection program" (actually the fence was to protect my pets). I added this sign that is a copy of a used target practice that says, Nothing in this house is worth dying for. The last time and elder came by I did talk to him. I gave him several reasons why I felt the jws. He returned and sat out in his Humvee flashing his lights into my house. I just had a drink. He put a note on my fence. He wrote "I've been thinking about what you said all week. Carl" If he started to climb the fence it would have freaked me out. Thankfully he didn't. He actually is a very good man but he has a dominent wife and a really crazy daughter (in her 40or 50s) living with him. He can't get out.
You don't have to please them or do anything for them. Just blow them off as they have you.