I would recommend Algin, because it binds to nickel as well as mercury.

Magnesium is also very important because it has been shown to be a competitive antagonist (a substance that blocks or nullifies the actions of another) of the toxic effects of nickel.

Since she doesn't have amalgam fillings, then she could take a formula like Heavy Metal Detox, which contains algin, magnesium and other ingredients that help promote the elimination of heavy metals and protect the cells from the effects of heavy metal exposure. Even though this product contains some algin, I would personally take extra algin to ensure that all the nickel is being eliminated (along with the mercury).