@Jim222 

I think you may be referring to a 4-way switch layout? 

There have been other threads of users trying to install the HS210, worked for some, not for others.

We don't have material regarding 4-way setups so you may need to look at a third-party solution.

@Jim222 This may not be the way you want to go, but it worked for me.  I might also add that I am very pleased with the performance.  I added a Samsung Smarthings hub to my home network and purchased a push button to do this exact thing.  Took minutes to install and I also use it for other actions.  Let me know if you need more of an explanation on how this works.  The button is only 14.99 but you need the hub at 69.99 to make it work.  Of course, after you buy the hub then you can do alot more things with it.  I linked my Kasa account to Smarthings and the only thing I use the Kasa app for is to view the cameras.  All of my unlimited number of smart actions are done through Smarthings.  Bite the bullet and buy the hub and button.  You won't be sorry.  They also have motion sensors, etc.  

button - https://www.bestbuy.com/site/samsung-button-white/6265829.p?skuId=6265829

hub - https://www.bestbuy.com/site/samsung-smartthings-hub-white/6265835.p?skuId=6265835

Thanks Tony, Thanks KasaUser005.

I guess I'm not good at explaining.

Not looking for 4-way, as the spot where I need a switch has no existing switch or wires.  I want to replace the existing two 3-way switches with 3-way smart switches, then have another switch - battery operated - that I could put on the wall outside our master bedroom.  Then I want this battery powered switch (remember, there's no wiring to the wall outside my bedroom) to send a wi-fi signal to the other switches to turn the hallway light on/off.

KasaUser005 - I think your Samsung Smartthing idea would be perfect, but I want a switch outside the door.