Hi Rog,
I think this answers my questions:
"As far as I am aware any settings that you organise for a rhythm apply also to the fill-ins."
I suppose regardless of what you have in settings in the play mixer, playing a fill-in will play the settings you did for it in COMPOSER.
I must make something clear that I didn't state in my question, I am speaking of volumes set in each part in COMPOSER.
Thanks,
Mark