I'm making a bunch of dolphin cookies for my daughter's birthday.
I made a huge batch of Royal icing using Antonias recipe.

Do you think if I wanted to add additional flavor and some corn syrup for shine, that I can do it after the royal icing has already been sitting?
I am going to add some more powdered sugar as it seems to be rather runny. If I add the previous and then more sugar, what do you think?

Also, how long would you leave cookies before eating? Party is Sunday. IS it even worth freezing if I'm baking today and decorating tomorrow?

Thanks!

Add flavorings then get the thickness right. I always thicker for edging and thin to flow. I think they will sit (depending on temp and humidity) 2 days with no problems, covered of course. As for the corn syrup - I cant really see where it shines - but yes, I have done it!!!