I am afraid Chanca Piedra does not increase the bile flow, it only softens and crunch stones.
What helps move the stagnant bile are: Chinese Bitters and Artichoke Tincture.
Remember your bile should flow well so that your digestion is fine and you are able to digest fats in genaral. This means a healthy gb and liver.
The risk of a gb attack does snot seem to be connected to a good bile flow, but the opposite.