Okay, so first of all, I've made SMBC beofre, twice actually, and it turned out great. But, for my little sister's birthday (she specifically requested SMBC because it 'tastes like a vanilla marshmallow cloud'), I have too make a very large batch because it's a big cake. So, I want to know if it would be possible to use Wilton Meringue Powder and the amount of water specified on the container instead of egg whites. TIA.

I have never done that myself but I did use a recipe that is a mix of egg whites & meringue powder.  It may have been my imagination but I felt like there was a taste to it.  I don't know how to describe it but I won't be using it again.  

Thanks for your reply. Anyone else have experience using only meringue powder?