space the width of key signature

[Br. Gabriel-Marie | SSPX]

There is this one song that is in c-minor and so the key signature shows the three flat signs at the beginning of each staff.

But c-major doesn't need any extra signs.

However, I am numbering my lyrics like this so that I get numbers on every line:
\new Lyrics \with { instrumentName = "8." shortInstrumentName = "8." }

\context{
\Lyrics
% **** Verse numbering using instrumentname
\override InstrumentName.X-offset = 3
\override InstrumentName.font-size = 0
}

This puts my numbering just under the three flat signs in c-minor.

But my problem is that in c-major the lyric text overlaps the numbers.

So, how can I insert a "blank" in the staff where I'd normally have the three flats?  (I'm looking in the docs at \staff and horizontal spacing....)