Steven Hassan gives a lot of good tips for writing letters in his book, including a sample letter to a fictitious cult member.
He says sometimes it's helpful to write what he calls a "purge letter." That's a letter where you let it all out but don't send it and then get rid of it.
For the letters that you will actually send he gives this advice:
Steven Hassan in Releasing the Bonds wrote:
. . . Writing Letters
Letter writing is a powerful medium of communication, and I recommend making each letter count. It is the one mode of communication in which you have total control. You should think, plan, and utilize letter writing as the foundation of your communication efforts. As always in the Strategic Interaction Approach, your first goal is to develop higher levels of rapport and trust so that he will look forward to hearing from you and want to correspond. The next goal is information gathering. Once you have achieved a high level with these two goals, you can move on to advanced techniques. The following suggestions may help you in composing your letter.
- Start warmly and end warmly.
- Keep it short (avoid long-winded treatises).
- Focus on one or two key points.
- Restate points raised in past telephone calls and letters.
- Ask follow-up questions to past interactions.
- Coordinate letter-writing efforts with others.
There's a lot more stuff on this in that book and a great deal on working toward and achieving the goal of getting your loved one out of the trap they are in. Getting it and reading it may help a great deal with that. But if you don't get the book one thing you can do is write letters to your loved one who is in, even if they don't get them or read them.
The other point with writing letters is to keep copies of them per my first post on this thread.
By the way, "the strategic interaction approach" is a method for getting a loved one out of a cult. Hassan evolved that method from the intervention and deprogramming methods outlined in his earlier book,
Combating Cult Mind Control and most of
Releasing the Bonds deals with the strategic interaction approach.
I suppose a person in scientology could get and read
Releasing the Bonds in an effort to counteract the methodology described there. The trouble with that is the book has been written using that methodology so a cult member reading it is very likely to find themselves waking up and leaving the cult they are in. (Is that some kind of challenge?)
A lot of the same ground is covered in both books. If you can only get one of them get
Releasing the Bonds but
Combating Cult Mind Control has information in it that I found therapeutic and that isn't in
Releasing the Bonds.