lead sheet chords position with \alternative

[libero . mureddu3]

Hi,
I'm writing a lead sheet with one staff with melody and chords and I have
the following problem: because I have some repeats (\alternative), the chords
are printed above it, and this creates lot of space between the melody and
the chords.
There is a way to move the chords closer to the melody, and to rise up the
the \alternative signs (if needed)?

Thank you
Libero Mureddu

lily 2.4.5
macosx 10.3.8