I would not mix it into either part of a two part unless you knew exactly what was in it (which is unlikely). It is not obvious you can.
If you have to try, put it into the calcium part and hope for the best.
Figure out how much they recommend to dose per day for your tank, and then how much two part you already dose to maintain alk (or calcium) and add those amounts together.
Two part dosing can be a great way to maintain parameters while helping corals' coloration, growth and overall health. Fauna Marin has two part dosing system that is combined with trace elements for color and growth, metabolic elements and health elements. Fauna Marin refers to their two part...