Answer : The IQ Panel 2+ supports up to 3 IQ remotes (QW9104-840) and 5 PowerG wireless keypads (WS9LCDWF9) with software version 2.6.0 HS2LCDWFx, HS2LCDWFxENG models are now supported as well.
Now with the 2.6.0 software version we Added support for DSC hardwire keypads (HS2LCD, HS2ICN) via the CORBUS on the PowerG Hardwire to Wireless Translator (PGxWLSHW8) with firmware v1.1. Also added new PGM system triggers for Police, Fire, Aux & CO emergency (limit of 2 hardwire keypads per PowerG Translator (PGxWLSHW8 for UL/ULc)
So you can have a limit of 12 secondary keypads all together on 1 IQ Panel 2+