t would be easy to have one Jeenode read the echoed serial commands from the Legacy base, and then send commands to other Jeenodes around the layout or in rolling stock.
just a question you gurus
could this also be used on a dcs System to control MTH animated cars
I don't think so - while it is possible, with difficulty, to transmit pre-specified commands to the TIU, MTH makes it impossible for users to read the commands being issued from the TIU.
If you have TMCC it is straightforward to use Electric Railroad Mini Commanders to control animated cars - if configured as an ENG, you can control them with the DCS remote through the TMCC base.