And they will leave. I have followed ringer friends through a handful of communities and lists that they have started and left or shut down. Change is the norm for ringers, and they leave for a million reasons. You'll never make them completely happy, so don't bother trying. They will get themselves in trouble with other list members, but they will just as easily smooth it over.
Ringers are accustomed to the attention, good or bad, and can handle themselves.
Since ringers are so transient, understand that anything you tell them, private or otherwise, may be told to someone else down the line. Decide what's private and what's public and never cross that line, no matter how long a ringer stays. Sustaining community doesn't interest her because once a community reaches a certain point, stasis sets in. I mentioned she should charge for her services. She said that she's considering it, but she's not sure of the market.