The short answer is that you can add MCHA to your Shine if that’s your preference, but MCHA is already the number one ingredient in Shine. So, it’s really not necessary to add more MCHA to it.
To explain a little more, here’s the backstory of why we offer MCHA in our online store: after we launched Shine several years ago, some members of the OraWellness community contacted us to let us know that they’re allergic to one or more ingredients in Shine and to ask if we had plans to make a version of Shine without that (some folks asked for it to be free of essential oils, others requested it without baking soda, others wanted no xylitol, etc.).
We don’t have any plans to make special versions of Shine, but we wanted to help these folks. So, we started selling MCHA (the main remineralizing ingredient in Shine) in our online store. That way, folks can make their own version of Shine and control the ingredients.
So again, if you’re already using Shine, you don’t need to add more MCHA to it. Although we see no problem with you doing this, in our opinion, it’s just not necessary because Shine’s MCHA content is already substantial enough to provide lots of remineralization support.
Finally, to give you an idea of how we’d intended for folks to use the MCHA bulk bags, here’s a link to our article, How to make a DIY remineralizing tooth powder (that really works).