I'm guessing, like me, most DOpus users like their keyboard short cuts, so I thought you might like this program " Multi-Keyboard MACROS" by MediaChance (I have no affiliations outside of being a costumer).
It allows you to add keyboards to your system and map macros to a single key without effecting the primary keyboard. Simply put, keyboard 2 can have the 1 key as copy without the need to press ctrl+1 and the main keyboard's 1 key is unaffected.
The program is new and I don't know if similar exist elsewhere.
I've set up a small bluetooth keyboard as my second one and it works well.
See https://mediachance.com/multikeyboard/ for details.
PS his realdraw program is handy for buttons.