It is better for her to stick with the ES or magnesium citrate. If she gets a stone stuck she will feel worse and it is not that she never did it before. Besides for people that don't want to drink it, they buy the empty capsules and fill them with ES, so they don't have to taste at all.
You can also follow Julia Chang's website http://www.sensiblehealth.com, she does not use ES, but if you have a problem you should have one of herbs in the house.