In some cases I want 8va / 8vb signs only available in the full score to reduce the spacings between staves.
Some instrument players are not always comfortable with certain usage of such, hence my feature request of making it possible to only add such signs to specified layouts.
Yes, this has been requested once or twice before. I think it makes sense, since we allow clef changes to appear when the layout is shown in concert or transposed pitch, to do the same for octave lines at some point in the future. I can’t say when this will be done, though.