The original plan was just something simple. Tap Hallis on the head with the flat of the blade of a knife as she helped Jack up, and mock her. But then that wouldn't make sense because your posts don't leave room for it.
So I thought, okay, so use the tripping and falling thing while they're distracted. But then that still wouldn't leave much room for it for the responses that happen afterwards. And Jack wouldn't be able to resist making maximum use of the distraction.
But in order for the conversation to go on, you'd have t be slow to react, so Jack would have to be undetected for a few moments. Beth would be the only character in a free position to notice and counter Jack.
You're free to counter and all as you will, and I'll edit accordingly.