First, usually the carcass is assembled and the face frame attached to the carcass.
Then they are attached to the wall.
First you attach one cabinet to the wall as your starting point. Often a corner. Plumb both directions, shim as needed and screw it to the wall. If it's above a counter then it helps to have a helper or some sort of brace under neath to hold it up. In your case since you have cabinets to set them on you should be fine to just plumb them without a helper.
You align the face frames of two cabinets (the starter and the next in the series), and once aligned clamp them and then secure them together and then shim as needed against the wall and fasten that cabinet to the studs in the wall.
Just keep doing that until you run out of cabinets or wall
If you don't want to remove those cabinets that you already have secured to the wall, you 'could' try and create frames, using the same method you would have used that consisted of stiles and rails and carefully construct them using the Kreg jig system as a few big pieces. I would use the Kreg mini jig on the walls of the cabinets to attach the frames. (use a clamp to hold the jig and drill from the inside towards the outside)
Carefully measure one cabinet and figure that your face frame should fill the space to the wall and half way between each cabinet. For the one on the side wall, make it and then clamp it to a cabinet wall and plumb it to the cabinet so there is continuity, scribe it, remove what you need to to follow the scribe line and then attach it to the cabinet. If your cabinets are plumb then your other joints will be, too, if not then at least they will all lean the same direction.

Make one face frame at a time. Secure it to the cabinet and then custom make the next frame (minding gaps and such), etc. until they are all on. Because your cabinets are already attached to the wall, the frames may not align as well, and one seem may show up proud of the next at least part way along. Not much you can do unless you want to bring out the hand place or sander and plane/sand them even.
Not certain if that's what you were looking for.