I think that as long as you don't mix the two together or take them at the same time you should be OK. Personally, I think colloidal or ionic silver is best taken as needed for a specific condition instead of a daily amount, and most will tell you that therapeutic amounts should be greater than a couple of teaspoons. More like an ounce or more of the really good commercial stuff like Utopia Silver or Mesosilver and up to a glass of the homemade stuff or the lesser commercial brands (provided that you aren't taking the large particle high PPM commercial brands, especially not with salt).
I am not sure how much MMS might deplete minerals - I don't like it because of the oxidative stress prolonged use puts on the body.