RobotStudio event

flexpendant interface

I currently have 4 x IRC5 on only one FlexPendant.
I want to create on the FlexPendant a common interface to four robots by using ScreenMaker
.
Do I need only one license FlexPendant interface or 4 licenses (one for each robot)?

Is the interface can easily manage four robots at once?

Is this it would be easier to use the PC SDK to create an interface on a computer and is there a need for aditional license to use the PC SDK?