Just if anybody in the future like me is wondering how to pass multiple values in a single parameter and lands here and scratches their head for a while before remembering basic PHP information… It’s been so long since I coded I’m not sure I could actually code anymore!
Anyway – you can pass multiple values as follows where you have set up the drop-down to allow multiple selections:
your-subject-menu[]=VALUEONE&your-subject-meny[]=VALUETWO
