Agreed. I know that works with the GE/Jasco’s, wasn’t sure about others.
Maybe I’m totally missing something, but how can you put the smart switch in box 1 (A)? The dimmer needs a constant hot on the Line (Common) terminal, right? You don’t have that at switch A. There are 2 travelers and the switched leg to the light. The red connected to the Line (Common) on A will only have power part of the time depending on the position of the switch in Box #2.
@Bry there is no hot currently to the existing switch, but there is hot in the box. Let me pull out my trusty MS Paint at the office and I’ll take a crack at modifying the diagram, it may come out looking like my 3 year old drew it though LOL
I understand. I was taking the drawing as the new configuration.
I understand that the hot has to be wired to the common in #! and “removed” from being sent to #2.
Which is how I stated the dimmer should be wired. I must have missed the part about the Aux switch.
@JohnRob the aux switch part was just me saying that’s what I would personally use instead of a dumb switch. OP has no plans of using an aux switch here, but if anybody in the future searches it the info will be here.
You guys rock! I am going to give MRobi’s suggestion a go when I get home tonight! Let’s keep fingers crossed 
I’ll update you how it goes. Thanks again for everyones help! Lol this is just switch #1 of 10 I am putting in. So lets hope the rest go better ahha! I’ve learned a lot on this now so if the rest of them are like this I have a pretty good idea of what to do now.
Glad to know this was a really “weird” setup and not just a regular wiring scenerio.
I’m not sure what you mean by "Line (Common) terminal.
In my diagram the known hot B-Black will go the Dimmer “Line” terminal.
John
Right. Disregard. I mistook your drawing as the implementation, not the current state.
You only get one consult per month, lol.
Solved! Lol 1 of 10 down! Thanks again everyone for all your electrical wizardry
It works and still maintains the 3way capability!
Now just gotta configure it. Maybe that will be another thread lol.
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Thanks for the final report. It makes us feel good you succeeded
I managed to get another 3 installed last night that had very similar wiring situations. Glad I figured this one out as it allowed me to figure out the others.
I’ve run into an interesting one now. In my garage, I’ve got a single pole switch, and the “exterior lights” switch (this is where the “other” dumb switch was in my example you were working on with me).
The single pole SHOULD be easy to wire except from I have no neutral in this box, unless I can tag a neutral in off that 3-way that comes in. Here is a photo of the switchbox.
So the single pole is the one I am trying to do. The 3 way switch you see to the left of that is from the diagram you were helping me from earlier. Can I in theory splice one of those wires and use that for my netural? Except I don’t think any of those wires ARE a neutral. So I am SOL for this switchbox?
Um, it’s not February yet. 
Is that Box #2 from the posts above? If it is then no, the white isn’t a neutral. If you look @MRobi 's diagram, the white sends the hot back to the light.
You might be hosed here, which is unfortunate. I don’t know the Canadian electrical code, but you stated the house was just built. In the US, a neutral is required in every switch box (NEC 2011). Not this is going to help . . .
What does that switch control? You might be able to use the dimmer (instead of a switch) in a no neutral configuration configured to just turn on and off.
That switch just controls my garage lights (the right switch).
The left switch is for my exterior light switch (it’s a 3way) and as I thought doesn’t have a neutral.
Weird that it doesn’t have a white neutral. Usually US / Canada building codes are pretty similar, and the house was literally only finished being built in Dec last year. So only a few months old.
So if it’s just the lights, maybe try the dimmer in a non-neutral config. You definitely can’t have an Inovelli switch with no neutral. Someone here or in the SmartThings forum posted some configuration parameters to make the dimmer act like a switch.
As much Romex as he left in the box for that switch, he almost could have made it back to the lights! <— j/k