Engine File for Blueprint are confusing. Shed some light here please

So for the past few days i been going back and forth to find how a Blueprint is created when called from the editor. I want to add a new Panel list where “Graph,Function,Marco,Variable,etc” are. I Added the name of the new Panel list its Called “OVERRIDABLEVARIABLE”. But dont know where to go from there i have been looking at SMyBlueprint.h, BlueprintEditor.h, BlueprintEditorUtils.h, EdGraphSchema_K2.h and all there cpp files. But still feel confused on how they get called and created is there another file im missing that i should look into.