What you can do is name the tracks that you want to send to the engineer. A simple thing I do is use CAPS to name group tracks that should be used for mixing. You could also prefix / suffix them with STEM.
So in your case I might have:
*** DRUMS
** cymbals
ride
Then when I export everything, I know to only send over the DRUMS.wav file.
Basically, just use some naming convention to identify the files to be used for mixing / mastering.