The only reason to force this disassociation agenda is to excercise control over someone and to instill fear into remaining members in my opinion . What do you say ?
I agree. My response: Don't give it to them. By signing a letter, you are perpetuating their agenda. By refusing to sign it, you are removing their control over you.
Here is the method I use with people who can't take "No" for an answer. State nicely but firmly your position.
Elder: "Please sign a letter of disassociation."
Heaven (states in a nice, pleasant tone): "Oh, no thank you."
Elder: "We need you to sign the letter."
Heaven (in a firm, business, matter-of-fact tone): "I believe I was clear. I am under no obligation to sign anything if I do not wish to. Shall I call my lawyer?"
(In certain situations, I replace lawyer with police. It has never failed me yet. Bullies do not deal well with having the authorities involved.)