How do I substitute sweetened condensed milk for powdered sugar in a recipe?

I Always Substitute Sweetened Condensed Milk for Powdered Sugar, Not Hard at All, I Add 1-2 Tbls Cornstarch to the Milk, I Haven't Ever Had to Rework an Entire Recipe.

The condensed milk will add more liquid to the recipe which would require more flour or the deduction of the egg. You can't substitute the sweetened condensed milk without reworking the entire recipe. My suggestion would be making a condensed milk cookie recipe like this one: http://floursandfrostings.com/condensed-milk-cookies-recipe/

Then adding the flavorings from the Shrewsbury cookie: toasted caraway seed and lemon or orange zest.