JD,
Well, one problem solved… The Eaton/Cooper Aspire 5 button scene controller WORKS FINE with my Smartthings setup… It added the controller, allows full access to toggling the lights, etc. and also easily lets me assign Scenes to the trigger of one of the 5 buttons on the controller using the Smart Lighting Smart App.
No tweaking or custom coding required… What a relief!
I have not yet attempted to add the 2 Leviton Scene Controllers, but this main one at the top of the steps was key to my setup… the other two are just for convenience.