Simulation on part of circuit

I design a device and it would be convenient for me to have main schematic (for PCB) and few other schematics for simulation to run experiments. On top of that, I’d like to be able to run a simulation on a selected circuit only.

Is that possible?

So far I work by having a dedicated KiCad project for the main circuit and PCB and every simulation, but it’s getting unwieldy.