How to best create this?

I’d like to create a font to draw guitar chord diagrams:

Would it be better to make a glyph for the blank diagram, then a glyph for each finger mark? Or should I make each glyph into a mark with one column of the fretboard behind it?

I think it is best to keep the blank diagram as a single glyph outline. That way you can more easily modify it later if needed.

If I do that and add the finger marks on top of it, won’t they be transparent? What I mean is, won’t the diagram outline be visible in the middle of the finger number?