Oats do not increase head retention. After a certain threshold, they even decrease head retention.Throughout the thread, only a couple of people have added flaked oats or oatmeal to their rendition.
Asking for general "in a recipe" advice. Not necessarily this recipe.
How, at what point, or how much/gal would one incorporate oatmeal for some frothy head retention and what possible issues, from using it, would I need to watch out for?
More on oats: A Case for Brewing With Oats - Scott Janish