They should quickly try get the rematch scheduled and make a deal with the IBF commission so that the winner has to fight the mandatory which I think will be the winner of Dubois/Hrgovic, though I also heard that AJ will be fighting the winner of those two so who knows. There's so many belts and mandatories it's hard to keep track of them all.
That is part of the problem, the number of belts that were unified when Fury and Usyk had their fight are simply too many to keep all their authorities happy when it comes to comparing the boxers they have ranked as number one contenders. For example, if the IBF want Usyk to fight their number one ranked contender but the WBC want Usyk to fight their number one ranked contender, things will get messy.
When it comes to the WBC, WBA, IBO and IBF forcing their champions to choose between accepting mandatory fights or surrendering their title belts, it really does become a sad situation.
The mandatory challenger is Filip Hrgovic, who will be fighting Daniel Dubois on 1st June.
If I understand the situation correctly, if Uyk's request is rejected by the IBF, Hrgovic and Dubois may end up fighting for the belt.
As hilariousetc stated, if the IBF decline the case put forward by Usyk the other way out of this could be to make a deal/payment for their number one ranked contender to step aside and allow Usyk to have the rematch with Fury.
I hope Fury and Usyk manage to have that highly anticipated rematch and I hope it will be for all of the titles. If their rematch goes ahead they both deserve
to be fighting for exactly the same belts that were on the line in their first encounter.