tranpose relative to the last pitch

[Tom van der Hoeven]

Suppose I have
music = \relative c'{c b a g     f e e f     g a b c}
my instrument is limited so it cannot play the pitch f end below
I have to raise  f e e f by a terts of an octave
Is there a function shift or can it be made such that

music = \relative c'{c b a g     \terts{f e e f}     g a b c}

is equivalent to

\relative c'{c b a g     a g g a     g a b c}

if you use :
terts =  #(define-music-function (parser location ploep) (ly:music?)
#{ \transpose c e \relative c' $ploep #})

the c' after \relative should actualy be the last-pitch (in the example g)
Help will be appreciated

Tom