Ted_B 4 buttons allows maximum 4 possible functions, the reason for 4 relays on the circuit board, 1 for each button. If you wish to add more functionality to any one of these four possibilities, you can drive the coil of more than one external relay from each of the circuit board relays. If using external DC relays, make sure you use a diode connected reverse bias across the coil of each external relay coil or inductive load. Likewise if using external AC relays, use a surge suppressor across each coil. This will help protect the contacts on the internal relay when operating inductive loads.