How can I extract two pcb within one schematic

hello sir,
I want to create two separate pcb from one schematic so that i can place one on the main pcb while interconnected to each other.
As u can see in screenshot, i want to place U7 as seprate pcb on the other one so i tred doing it using edge cut but its not happening
can any one help me for doing such?

KiCad’s workflow is based on a 1 project = 1 schematic = 1 board paradigm. There are hacks but that’s the main model. I would separate out the part of the schematic that goes onto a different board into a separate project. There is a FAQ about what to do with a multi-board project, have a read.