Oops, I meant to ask if the individual mentioned in the first post would be agreeable to a private practice/lesson with the director. Over time she might take a more studied view of her role, especially if she sees that she's got something to gain.
For a couple of years when shift work prevented my regular practice attendance I joined a weekly practice with an inexperienced tenor who sought help. It ended up being good for him to hear his voice with my bass voice, good for me to get the closer individual attention from the director, and good for the choir to have us in better voice. I wish it was still possible.
Anyway, is there any chance she would enjoy the extra attention?