Most of the 2 bedroom units at OKW are dedicated - only one entrance and no kitchenette in the 2nd bedroom. Unless the renters are family or very good friends, you probably would not want to share your unit with them.
If you have a lock off unit, this is possible. HOWEVER, both sets of keys would open the entrance to the 1 bedroom side and the entrance to the studio side. Again, not a great situation. I don't think the CMs can key them separately without changing the reservation to a studio and a 1 bedroom - then you have potential problems with waitlists plus it will cost more points than a single 2 bedroom unit.
I do not know how 2 bedroom units are assigned at OKW. I would suspect most are rented as separate studios and 1 bedrooms. FWIW, I don't think you have enough time to work out everything so that you can rent.
Isn't there someone else you could invite along? Sorry the relatives can't come, but since they cancelled so late, I say just enjoy the extra space - it won't be "wasted", LOL.
I did a 2 bedroom for 3 adults last December - It was very nice to have a bed for each person (we were cousins, all females) and it was also nice to have the kitchen/living area free for those who stay up late or get up early. The extra bathroom was a nice perk as well.
Best wishes -