Sire V7 - Series / Parallel Mod

Hi, folks! I have a Sire V7 bass and was wanting to mod it with a series / parallel switch. It’s a great bass as is, but would love the versatility of being able to run it in series

I have a buddy who’s done some electronics work that says it’s not possible on this type of bass, due to electronics setup, without making the blend knob unusable / knocking out volume from one of the pickups

Has anyone done this mod successfully? Would appreciate any advice on this, as I’m not super familiar with electronics modding possibilities!