Hey, Andrew,
I remember using Bbs on Tchaik 4 about 40 years ago...no problem, just pencil the notes in - better yet, use pen!! BTW, was it your idea or the conductor's? And I assume we're talking pistons, not rotaries?
Have fun - maybe you guys can use them on Alpensinphonie nnext time! :^)>
Best, Chas
Editions Bim and The Brass Press, International Music Publishing