Can you assign a fader to whatever the console has currently selected?

For instance, could you select Group 11 and control the intensity (having the ability to control color as well would be nice) and then later select Group 22 and be able to control the Intensity using the same fader? IE, not have a designated separate fader for each one? (Its useful to have a dedicated fader for often used fixtures but could you have a fader control the intensity for whatever is selected? In my case, what if you connect the lighting console to a MIDI board, and the board has few faders but many buttons. It'd be useful to set the buttons to select certain fixtures since there are so many and be able to control the intensity of the fixtures selected. Rather than have a separate fader for each)