@board4mic 

thank you for the diagram.  Did you replace both 3-ways with Kasa 3-way switches or just one of them?  Did the system know if the lights were on or off?  Did the scheduling function work?  Thanks in advance!

@board4mic I have this setup and it works for me. I REALLY wish there was a four way switch to replace the dumb switch, as I want all my switches to match. 

This is how I feel. I want all of my switches to look the same. Each of my switches (5 of them to control one light) are all located on a 3- or 4-gang switch box, so having one of them different drives my OCD nuts. Don't like it at all! I'm going to try to make the 2 switches that are not on the ends of the circuit not part of the circuit, so I can have a 'smart' switch that triggers the 'actual' switches via automation. Hopefully that will work.

Has anyone tried 4 way with KS230 3 way dimmer switch?

@Chicago_SH 

So If i understand this correctly, you don't need a special companion switch or something. Just replacing the normal 3 way switches from Kasa you can continue to use the mechanical switch  for the 3rd location in a 4 way config? 

@Chicago_SH confirmed to work. Just followed directions, placed it in the 2 switches that have laser wires. 4 way has 2 red and 2 black.. where as 3 way has 2 black and 1 red. Went through the pairing instructions. Worked like a charm. Thanks for putting those directions.. I think TP should publish this to avoid searching. I don't know why some say it's not working .. 

@HappyKing 

What's a laser wire?