Is it possible to increase the quantity of CAN connectors in one Drive PX 2?
You can just add some Linux/SocketCAN supported CAN-USB adapters via USB to your PX2.
I would suggest the PEAK USB FD adapters or the CANUSB adapter from 8devices (Classic CAN only).
I would NOT suggest CAN adapters using the slcan driver (which are mostly low cost adapters with the SLCAN ASCII protocol). Only native USB adapters (you can find in linux/drivers/net/can/usb/*) support proper error reporting and error recovering.
I successfully used the PEAK USB FD pro on my Drive PX2 Chauffeur board yesterday.