I want to use expression maps with midi channels. Can I have more than 16 articulations?

If the library lets you select Articulations via Keyswitchs then typically you can use a single instance of the Instrument to play X different Articulations. If you add a 2nd instance and put it on MIDI Channel 2 you get another X. Another instance on Channel 3 gives you 3X.

Here is how I set up something similar for Session Horns Pro which has 9 Articulation ‘Slots’ but a total of 16 Articulations. So the first 9 Articulations are on Channel 1 while Articulations 10-16 are on Channel 2.