Wiring help: 3 video doorbell pro 1 mechanical chime

I want to install 3 video doorbell pros to an old Nutone mechanical chime. The photo below is the old wiring and the chime can support up to 4 doors. I need assistance with wiring of transformers to ensure I have enough power and the pro kits. I spoke with some and they said use 2 transformers but they didn't say in series or parallel. I appreciate the assistance.