Full duplex communications

[Jdo300]

I'm not sure if this is a bug or not, but I am using scenario #1 where I have a program communicating with a hardware serial device and I want to clone the hardware port so I can both monitor and communicate with the hardware device along with the program I wrote.

So far, I followed the instructions to create a ttyS1mux, attached it to my ttyS1 hardware port, and then created two fake ports, ttyS1fake0 and ttyS0fake1. My question is should I be able to do full-duplex communications between all three connections? I found that I could send serial data through either of the fake ports to the real port, but for some reason, data sent through the real port doesn't arrive to either of the fake ports. Is this by design or is there a way to get bidirectional communications?