Maintain Default Touch Bar and offer custom buttons as alternative

I programmed a few "universal" buttons for BTT (full screen, swap screen", but when I use BTT, it buries the app specific buttons (and then puts an "x" to make the universal ones go away).

I really want it to show the default settings if there ARE app specific buttons and then hit a keyboard shortcut or "x" to show the "universal" buttons.

Is this doable?