I'm not familiar with "Mirto". What is the flavor profile?

Mirto rosso made from the myrtle berries is both red and sweet; that is what I have used here. Mirto blanco is made from the leaves. You can order mirto online if yours is one of the states which permits alcohol to be delivered. I love the complexity of it.

It's a Sardinian liqueur made with myrtle berries. Here's a link if you want to make your own (haha). http://honest-food.net/2010/10/30/making-mirto-a-sardinian-liqueur/
Maybe sub elderberry liqueur? Or blackberry brandy?