@Carl I have a similar situation. My old switch has two back stabs and a 3rd black wire on the side screw of the switch. I'm installing smart switches that only allow 4 wires (live, load, neutral, ground). So on the new switch I connect the live and the load, what do I do with the 3rd black wire?

@ctenner32 

When you have three black wires, the situation is going to be one of the two following 

a) the single black wire terminal is the Line and the two together on the other terminal are to two separate loads (lights) 

or 

b) the two black wires together are line - the terminal is simply being used as a junction to carry the line onto the next circuit (wherever that might be) (actually if you separate them only one will actually be line and the other only becomes so when it is connected that other one) 

Before disconnecting, use a voltage tester and determine which terminal in 'live' and that will tell you which of the above you have. 

But regardless, it doesn't really matter in the case of an HS200, which gets line and which gets load - so the important thing is just to keep the two wires that are already together, together to whichever you select on the HS200