So then we should simply use a slots-per-plug: * for both cups and cups-control for both connect and auto-connect. As there is only one cupsd on the standard resources (if at least one instance of CUPS is installed) the correct thing will happen when the user application’s plug plugs both the system’s slot and the slot of the CUPS Snap.
Is this how slots-per-plug is implemented in current snapd?
Where have the slots-per-plug: * declarations to be done?