Layout Set Staff Size

[Silvio ARDITO]

I need the following layout:

The result is a copy and paste from 2 .ly.
The little up-right staff  uses: #(set-global-staff-size 11) ;
the rest uses: #(set-global-staff-size 20) .
The command: #(layout-set-staff-size 11)
in the \layout section gives a not valid result.
Are there same (scheduled) enhancements since
http://thread.gmane.org/gmane.comp.gnu.lilypond.general/66291 ?

Thanks.

Silvio