This is how it looks now:
The -ve from both power supplies are bridged now.
All + & - from the sensors (brown/blue) are connected to a 12v Terminal at the z-axis.
All black signal wires go to the control box in one 3x0.75mm^2 wire.
The signal wires go from the blue terminal to the simple build with WAGO clamps and a diode between each pair. From there the signals go to BOB.