a) The tribes will merge at 11 instead of the typical 10 members.
b) The tribes will be rebalanced with one or more Koror members going to Ulong.
c) The RC and IC will run as always with a special proviso allowing one Koror member to sit out both challenges.
d) Koror will sit out 5 for the RC. Then, for the IC, they sit out only their other three tribemates. To compensate, one or more Ulong members must do something multiple times. (This, obviously, will not work if the challenge involves the entire team doing something at the same time.)
e) There will not be a RC, thus making the "back-to-back" challenges rule a moot point.
f) Other.

Option f) may be that they are allowed to substitute a player while the competition is happening