Hi again @pcanal,
So combining what I learned here with what I then found searching around (https://root-forum.cern.ch/t/ttree-draw-and-functions/879/6), I was finally able to revise the macro to do what I wanted it to do.
iterativeBayesTestThermal.C (10.0 KB)
Has there been any changes to the behavior of TTree::Draw()
since the message thread in the link above?