How to control 2 independent key-switches in expression map?

I’m looking for some advice on how to best set up an expression map to control 2 different sets of key-switches which are independent of each other. I just got a vocal library that has one set of key-switches to control the vowel being sung and another that switches between staccato and sustained. I know I can build 2 slots for each vowel one sustained and the other staccato. But that seems kind of like overkill. If say there are 7 vowels that method would require 14 slots. But it seems like I should only need 9 (7+2) slots.