Each side of the seat has two sensors - they’re the silver rectangles. Each sensor is connected to a wire and when the wire is pulled, the cap shows three pins.

 

The wires from each sensor converge to this one plug.




That plug is inserted into the weight sensor module which is then connected to the seat control module.

It looks like the control module then connects to the car’s wiring harness.

 

Lousy photos but hopefully you get the gist.

 

Beautiful seats!

But now I see the complicated setup, oh dear...

However, why dont you swap the complete seat console including all those gobbins?
The seats are bolted to the console with 4 screws. See one of the screws on the lower right of the pic.
That would be my last resort...

 

Unfortunately I don’t see a way to insert the four seat sensors between the recaro side supports and the rails.