I think most people would add the sugar to boil, as opposed to the primary. Regardless - and someone will correct me if I'm wrong - you will calculate a primary addition in the same, as adding it later shouldn't decrease it's fermentability.
Did you use brewing software? If so just add sugar to the recipe and see how many points it adds. Otherwise, I'm sure someone will chime in with a calculator or formula.
Also - I just learned that Penguins are Scottish chocolate bars. Never met a joke I didn't want to understand!
In Process - Russian Imperial Stout, Nelson Sauvin Rye IPA, Mild No.3
In Kegs - Barley Wine, Apfelwein, Wild BlackBerry Wheat, Coffee Oatmeal Porter
Gone - so many :(