Here's another script--
when she's telling you how you "ought to do it," say, "I'm going to interrupt you, Monkey, and ask you to hold your observations for now. One of the reasons for changes this year is so that new people can find new ways of doing things. Joan, please continue."
Basically, think like an air traffic controller, and just direct people to speak.
And the phrase, "I'm going to interrupt you, Monkey..."
Oh, yeah, sure, technically interrupting is rude, but it's not in this situation--not at all. And just be blatant about it. "I'm going to interrupt you, Monkey, and direct us back to the tasks we want to accomplish."
"I'm going to interrupt you, Monkey, so that the committee's actual members can speak."
"I'm going to interrupt you, Monkey, and ask you to hold your comments so that the committee can work."