I just joined this forum to thank telloy3k for posting a thread to connect a v1 and a v2 at the same time! His idea and wiring diagram allowed me to use my old v1 and wireless chime on the side door when I upgraded to a v2 for my front door.
His idea seemed sound to me and all I did was to upgrade my 10VA transformer to a 30VA.
The v2 rings my mechanical chime without any buzzing and the v1 connects perfectly to the wireless chime.