guitarist: how write chord names like Gadd5

[Jürgen Ibelgaufts]

Hello,

I want to write down guitar chords and frets with extra voicings, say a G chord 
with an extra Fifth on the B string, 3rd fret, or Em chord with an extra G on 
the treble e string. As these extra notes belong to the chords, you can write 
g:5, but Lilypond ignores the :5 and prints only G, and the G fret diagram gets 
overwritten by the G:5 fret diagram.

Is there any best practice how to use and print such extra chord names, anyway?

TIA
Jürgen