You can register up to 8 actuators per button group. e.g.
Button group 1 up to 8 switching actuators
Button group 2 up to 8 tubular motor actuators upper floor
Button group 3 up to 8 tubular motor actuators first floor
Since the Multiple Wall Controller recognizes which device type is registered and the grouping is carried out automatically, it is not possible to mix device types. No tubular motor actuator can be registered together with a switching actuator on a pushbutton group.