Looking to Echo Serial 0 to Serial 2 - Marlin 1.X (no replies)

Hello,

I'm looking to control my printer via USB with a host program, but I would also like to read values over serial on a second device. More specifically, I would like to parse an M114 command for axis position data.

I have added #define SERIAL_PORT_2 2 in Marlin, but curious how to echo all the data to this port as well.

Thanks!