Getting AMS this week for my P1P upgraded to P1S

My question is the firmware for the AMS, can I update it without updating the P1S? I’m quite content with the firmware I have on my machine. I don’t want to upgrade it. But I’m sure the AMS will need an update to match the printer? Also I would like to be able to share the AMS with the A1 that sits next to the P1S. Is that possible?
Thanks
M1