Creating a Control Set:
Method 1:
Drag a few controls to a window. Select the controls. Create a new control set using the Inspector.
Result: The events will only fire on the first control.
Method 2:
Drag one control to a window. Create a new control set in the Inspector. Drag other controls, adding them individually to the control set.
Result: Each control in the set respond to the events.
Interesting… in two ways…
One… you are correct… if the controlset is created that way… .it only first on first control member.
Two… I didn’t know you COULD create a set that way 
Always did it with method #2 (or method #3)
Method #3
Drag one control to a window. Create a new control set in the Inspector. Add other members by using the DUPLICATE feature
Result: Each control in the set responds to the events.