What usually happens, is that if a resolution makes it to the UNSC (most don't) then the P5 can either accept or reject the resolution. One "no" vote from any of the P5 members counts as a rejection.
In order to avoid problems in the actual vote, the P5 will usually negotiate the resolution in the back room, and "water down" the resolution to suit their needs.
The G4 have agreed to put in their bids as a group, which means the reform resolution will not be able to be watered down to remove any of the G4 members.
This can easily be solved if the G4 is disbanded. Then a "new structure" can be proposed that will not be vetoed by any of the P5.