The code I pasted uses a slightly different approach (built by the UI system). I copy/pasted that out of a plugin I sell so can’t really publish the code here (rdLODtools and has the source included if you already own it).
I think you’re “EditNum1->OnTextChanged.AddUniqueDynamic” is along the correct lines - what error does that produce?
Did you try “AddDynamic()” rather than AddUniqueDynamic()?