Pitch name change in the middle of a score

[guoguocuozuoduo]

Hi all,
 
I would like to know how I can change the pitch name input during the middle of a score (it is to be used by only one Staff).
 
For example, I would like to change this
 
pitchnamesBagpipe = #`(

(G . ,(ly:make-pitch 0 4 NATURAL))

(a . ,(ly:make-pitch 0 5 NATURAL))

(b . ,(ly:make-pitch 0 6 NATURAL))

(c . ,(ly:make-pitch 1 0 SHARP))

(cflat . ,(ly:make-pitch 1 0 FLAT))

(d . ,(ly:make-pitch 1 1 NATURAL))

(e . ,(ly:make-pitch 1 2 NATURAL))

(f . ,(ly:make-pitch 1 3 SHARP))

(fflat . ,(ly:make-pitch 1 3 FLAT))

(g . ,(ly:make-pitch 1 4 NATURAL))

(gflat . ,(ly:make-pitch 1 4 FLAT))

(A . ,(ly:make-pitch 1 5 NATURAL))

(B . ,(ly:make-pitch 1 6 NATURAL))

(C . ,(ly:make-pitch 2 0 SHARP))

)

pitchnames = \pitchnamesBagpipe

#(ly:parser-set-note-names parser pitchnames)

 

to this:

 

pitchnamesBreton = #`(

(G . ,(ly:make-pitch -1 5 FLAT))

(a . ,(ly:make-pitch -1 6 FLAT))

(b . ,(ly:make-pitch 0 0 NATURAL))

(c . ,(ly:make-pitch 0 1 NATURAL))

(cflat . ,(ly:make-pitch 0 1 FLAT))

(d . ,(ly:make-pitch 0 2 FLAT))

(e . ,(ly:make-pitch 0 3 NATURAL))

(f . ,(ly:make-pitch 0 4 NATURAL))

(fflat . ,(ly:make-pitch 0 4 FLAT))

(g . ,(ly:make-pitch 0 5 FLAT))

(gflat . ,(ly:make-pitch 0 5 DOUBLE-FLAT))

(A . ,(ly:make-pitch 0 6 FLAT))

(B . ,(ly:make-pitch 1 0 NATURAL))

(C . ,(ly:make-pitch 1 1 NATURAL))

)

pitchnames = \pitchnamesBreton

#(ly:parser-set-note-names parser pitchnames)

 

\with did not work.

 

A reply would be much appreciated.