pondering the 300 sq ft display

so i was looking at my pics from the WOC and began to wonder.  it's
not unreasonable to expect that all the vandas on the front side of
****hs' display came from RF; but what about all those white phals on
the back?

do exhibitors have to use all their own plants?  can they buy plants
from other folks?  after all, if everything you want to use in a
display isn't in bloom in your own GH at the time you want to use it,
do you change your design to reflect what you have, or do you go to a
mail order house or someplace else to get what you want?  does this
affect judging at all?

just curious, as i know nothing about all this....

--j_a