Hi Abby,
Unfortunately - this will not work with passive speakers.
But now that Lee identifies the cross point for the JBL's (100KHz), it's an easier task.
Dial the 100KHz cross point on the sub and there should be no redundancy in frequencies.
One more thought ...
I know I may be out of line but perhaps you should consider a different PA system mainly as you gig every night ...
I'm using 2 L1 compacts for small venues (up to 70 people).
I'm using 2 EV Evolve 50 for mid size venues (up to 150 people)
I'm using my EV ZLX 12" and EV 18 sub for anything lrger than 150 ...
All are powered.
This allows me to reduce the mixer to a small Mackie ProFX12V2 (very small and light) ....
This saves a lot of room in the car (...and a lot of weight off my back).
The L1's and Evolve's are taking less than one min to setup and tear down ....
Absolutely recommended.
Cheers!