I could be wrong (as I have never used FrameIt macro), but from what I see in the manual the only mentions of joining roofs are in relation to the RoofIt macro. I expect that FrameIt does not offer a join option (I'm sure somebody will correct me if I'm wrong).
You may be able to manually edit 2 overlapping roof frames after creating them with Frameit, but that would be a reasonable effort. Tools such as the Knife option in Bill D'Amico's 3D Tools macro would be helpful here, but you would still need to manually add valley rafters and boards etc. It it is normal to have opposing jack rafters match up on either side of the valley rafter and I think you would need to be reasonably lucky if the rafters from the 2 frames did so even after cutting the joint in... A fair bit of complexity which is probably the reason why the option was not coded in the FrameIt macro.
The Roofit macro should work ok in DataCAD 22 though.