My basement step lights and my Basement lights are on 2 different circuits. They bothe end up being 3 way switches because the steps have a switch at the top and the bottom and the basement has a switch at the back door and the bottom of the steps. Ugh
We’re constantly leaving one of those lights on
Can I use a smart switch in each circuit and program them somehow so they are always in the same mode? I never want them to be seperate
Yes. This is pretty easy with SmartLighting which runs locally as long as your switches do. Also pretty easy with WebCoRE which needs the internet.
If the switches are z wave you may also be able to setup direct association, which doesn’t use the hub.
Just note that in order to work smoothly it is likely that you will have to replace all four switches with smart switches: basement top of steps, basement bottom of steps, Basement circuit one, basement circuit two.
Then you can set it up so that turning on any one of the switches turns on the other three. And off the same way. 
. (BTW, this is called “mirroring” on the SmartThings platform)
All very helpful tips thank you. Since I’ll be buying switches what do I look for as far a the feature being built in?
I’m using SmartLighting “mirroring” for 2 Caseta switches and the delay, which used to be 2 seconds, has ballooned to 5+ minutes! I wish there was a native Lutron solution for this.
As long as all the switches are controllable by SmartThings, that’s all you need. Switch A will talk to the hub and then the hub will send a message to the other three switches.
You will hear some people talk about “Z wave direct association.” That’s a feature that works only between Z wave switches, and only some zwave switches. You need the trigger switch, but in this case that’s all 4 switches, to support that kind of association.
But these days, I do not recommend people use direct association, they almost Always end up unhappy. 
Zwave Direct association was invented before people used smart phones much, and the way it works is that the trigger switch is given permission to talk directly to the target switch without telling the hub about it.
The problem with that is it then your mobile app won’t necessarily know that the switches were turned on and it becomes much harder to set up other rules depending on the switches going on and off. You might save 3/4 of a second in lag, but you will spend a lot more time than that trying to figure out what exactly the statuses of everything. 
Zwave Direct association also cannot be controlled with rules or time of day or day of the week or anything else. It just happens bang bang every time. And there might be times when you want to turn off the lights on the staircase without turning off the light downstairs. Or Only light one section of the basement.
Direct association is an old technology that was suited to an older lifestyle. If you already have a bunch of Zwave classic devices (that’s the older generation), then, sure, it may be your best option. But if you’re starting out new with zwave plus devices, there are other, better options now.
The primary replacement for it is “central scenes” And many of the newest (2016 or newer models) zwave switches support that. (Note that the word “scenes” is used in many different ways in home automation. So we are not talking about smartthings scenes or Z wave local scenes or hue scenes. Just specifically “zwave central scenes“)
With the central scene, the switch sends a message to the hub and then the hub sends messages to the other devices in the scene based on rules that you have created. So that means you can put all kinds of restrictions and “if A unless B” And all that. And the hub knows what happens, so the hub and the app are always up-to-date on the statuses of all devices.
I’m not 100% opposed to zwave direct association. Its biggest advantage is that it will work even if your hub dies completely. So if you had a switch at the top of the attic stairs and one at the bottom, I might use zwave direct association for that. Most of the time you aren’t going up into the attic anyway, so it’s unlikely you’re going to want to put other fancy rules around it. And it’s a good safety feature to make sure they always work.
But most of the time I think people prefer the accuracy and flexibility of central scenes. 
Ouch! That’s horrible.
Lutron’s native solution for this is to use picos for the accessory switches. That’s what they sell in their three-way kits. But I know that doesn’t help your situation.
By any chance do you have an iPhone? You can use HomeKit to create a virtual three-way between two Lutron Caseta switches and it all runs locally and is very fast. ( I use this in my own home) So if you are already using Apple devices, it’s a good choice.
5 Minutes has to be an issue with the smartthings cloud. Which means it could get better again in the future, but I know that’s not much comfort now.
Yep, the picos work fine but would look really odd mounted on top of the switch :). I use Android so no Homekit virtual switches for me. I’m hoping SmartThings fixes their cloud issues soon - it worked great when I first set it up but is useless now with the delay. I’m going to look for a surface mount box for the pico to fake a 2-gang look and pray my wife doesn’t look at it too closely!
Your picture would actually work for me if the pico doesn’t require a hole in the wall! How is the pico mounted in your case?
That’s just a random picture, not my house, but what happens is lutron makes a piece that fits into the wall Where the switchbox is and holds the pico in place even though it’s not wired in. So you remove an existing wall switch and put the pico there. So what actually is going into the wall, not just surface mount.
https://www.amazon.com/Caseta-Wireless-Wallplate-Bracket-PICO-WBX-ADAPT/dp/B00JZRAFEA
If you want to surfacemount it and have it look like a double gang switch you need to get a switch box extension piece that lifts the wired switch up a little bit to match the pico position.
The extension pieces are cheap, usually two or three dollars, and you can get them at a Home Depot. People use them when they have tiled around an existing switch area In a bathroom or kitchen. So that gives you an extra 3/4 of an inch or so.
There’s a topic in the forums discussing those for people who bought a smart switch which is too thick for their existing switchbox, it might give you some ideas:
sorry, I just realized you were not the original poster for this thread, and we are getting very far off topic. Please start your own thread on wall mounting Lutron Picos and we can talk there.
Thanks for the detailed answer, I don’t think I’ll need the direct association, I’m fine with using it through SmartThings. It’s at our lake house so it will be a while before I try it. I’ll have the added ability to turn the basement lights off if I forget and leave them on!
I’ve been trying to think how to rewire this stuff for some time I wish I would have asked for the SmartThings solution sooner
If the switches are using dth that run locally, the mirror smart lighting rule will run local.