Multiple collisions with cloth - bedsheet on bed

[irte]

Hi all, I'm a cloth newbie.
I've finally got a bedsheet draped over a bed in maya
thanks to the tablecloth tutorial,
but now I'd also like that bedsheet to drape over a sleeping sphere in the bed. If possible I'd also like to animate that sphere moving and have the cloth move with it.
So now that I've got it draped over the bed, how do I make it drape over the sphere too?
Thanks!

[drblacksnake]

make sphere as a collision object do additional sim, either
A. put it on the bed and "drop" sheet on bed again;
B. put sphere under bed and animate its movement upwards, so it will appear on the bed like in horror movies.