I was paying attention to the chat this morning with Evelindecora and royal icing mix from Squires Kitchen. I looked at their website and as is mentioned here, there doesn't seem to be a comprehensive listing of the ingredients. So, here's my question...since SK RI mix contains vanillin is it wise to further flavor it? I usually use vanilla, almond extract and butter flavoring in my RI. Should I add the almond and butter flavorings should I decide to try the RI mix? Also, I'm not particularly fond of the really hard RI and always use glycerin and/or light corn syrup
as a "softener" to the icing. It didn't look like glycerin was included in the RI mix from SK. I do believe that I read somewhere that it's ok to add 1 tsp of glycerin to 500g of SK RI. Anyone have any experience with any or all of this? 
(Sorry for the long post.)
I've used Squire's Kitchen (and other) royal icing mix; it dries hard all of the way through, as it's mostly just sugar and eggs with some flavorings (there is a complete ingredient list on the package). But my experience is that most of the mixes are flavored rather heavily with vanillin. You can certainly flavor over it with more flavoring, but you might need a little more that you are used to adding.
Thank you, Julia! I really appreciate the feedback. I've decided to give it a try in a small quantity (mix and shipping is $$$$). Will provide feedback when I use it .