USB Bridge Mode

I currently have a UMH-21 and would like to send all the USB MIDI outs to the USB MIDI ins. This is a type of bridge mode or broadcast. It is similar to plugging the MIDI out to the MIDI in. Note: The sending USB MIDI out device however should not receive the same message on its MIDI in device or hear its own echo. This would cause an infinite loop.

Situation: I have a USB organ emulator (MIDI in/out) and 2 USB keyboards (MIDI out). I would like to simply connect them through the 4 port hub.