There might be a few ways to do this (OptoMary will probably have 10 different ways....), but its a classic issue that many of us face.... Having a UI (User Interface) and a program (Strategy) controlling the same output.
At the class here at Opto, I always strongly suggest that people design the UI FIRST and then write the strategy.
Sounds like you have had the strategy running for a bit and then added the groov UI.
So, in this case, I would attach groov to a variable in the strategy, have a little code that decides if groov (the user) or the strategy should write to the VFD.
You, and only you, can decide what the deciding code would look like.
Bottom line, the drive can not read the users mind and chose which of the two devices writing to it should win.
You, the programmer, need to decide for it.