Pickup with 3 wires

Hi, I’m the New owner of a 2021 ebmm sterling5. Suppose to be wired in series except both humbucker in parallel in position 3. If you take a look on picture, pickups only have 3 wires. Black, red and green. How can they split coil in position 2 and 4 with only 3 wires? Can I install a switch to have my Humbucker in parallel in position one when I need to?