Adding Addition Wiring Diagram Chime. I used existing doorbell wiring for my Nest Hello and only use my Google Home Minis as my chime for visitor announcements. The wiring of the second chime is not too difficult.
Secure the white wire to the top terminal and the red wire to the bottom terminal located on the back of the doorbell button. Heres a simple doorbell extender kit. Strip about 12-inch from the ends of each wire.
When attaching the new chime at the transformer connect the new wires to the same wires and screws that the wires from the old chime.
Connect the input wires on the transformer to the source circuit using the black to black white to white and ground to green method. IOW the new chime would simply be wired in parallel with the existing chime so both would sound at the same time. You will need another transformer to wire the two bells together. The rear terminal is where the rear doorbell push button if you have one connects to the chime.