There are different Liver Flushes and you can check under cleanses at top of this page. For the Gallstones she has to keep flushing may be 10+ x, like every 2 weeks, she should not stop with 1 or 2.
She should also read the FAQ at the top of this page, there is lot of information there.
If she feels an attack come up tell her to dissolve 1 tbs
of Epsom Salts (=magnesium sulfate) in warm water, drink it and she should feel better within 20 minutes. It does not taste good but I have been putting a few drops of stevia in it and it still worked.