I kind of hope that if the parish council gets shirty enough, she’ll say, “It’s them or me!” ... and the pastor can’t fire the parishioners!
The problem with people who have held a position like that for so very many years is that they think they are indispensable and usually find out, to their chagrin, that they aren’t. They can be and most often are replaced.
Which surprises them, but knocks them down a peg or two. Maybe it’s her turn.
Good luck on this. I know you’ve been fighting this for quite some time now, and it’s time to rein it in and bring it to a halt. There’s absolutely no reason whatsoever for this to have escalated into such a major production.
It could have been solved long ago with a little cooperation on her part.