Concerning the button: It would depend if they use separate or shared port addresses. My KS6 share the port so what happens on one is the sames as for the other. I believe the Linx2 and above have separate addresses. It a design decision that probably isn’t that cost effective at least compared to the perceived benefit for the user.
For those who don’t understand ports, it is a common way used on computers to allow signals to interrupt or provide information based on how the design specifies. Things like printers and USB have port addresses where they can send or receive data. If it is for real time programming, the design criteria is far more precise. It can go beyond what a normal computer’s service timing typically needs.