Proper piping for VC Montpelier Insert

[Rlucas93]

Hello all, hoping to shed some light on an instal I’m looking to do in my home. Last year my family added a 2nd story to our house. The cost to repair and extend our chimney was more than the framing material and then some for the addition..so, we demoed the chimney to the “offset” leaving the fire box and some space above it. The fireplace is a focal point of the 1st floor so in an effort to keep that left what we left. Pictures will be provided to help with the layout but I got my hands on a Montpelier and would love to install it. Now with no full chimney, liner is out of the picture. My question would be. From the stoves 6” vent collar, could I connect insulated flex liner pipe from the stove to a class A double wall pipe adapter, terminate through the roof shown on what’s left of the chimney like a normal roof termination, continue up the side of the home using Class A? A few things to point out. The insulated flex liner would be in the firebox with no combustibles. The class A would be connected within the same space. I’d have proper adjustable roof support collar to support the vertical load or use a mounting plate within the firebox. I’ve been told that going single wall pipe to class A is only allowed with free standing, but im not clear on why that wouldn't be ok in the same firebox only with an insert instead. All parts will be UL approved, seems like there is continuity of pipe equipment throughout. Any input or photos of similar applications would be greatly appreciated!