Pretty sure this could be solved in a similar way to handling versions of a duplicate computer file, name the old EU file as EUv1, copy contents of v1 to a new EU file, make amendments to EUv2 using ctrl+f to delete mentions of Hungary (or preferably ctrl+r to change Hungary to UK, maybe rename the EUv2 file to SovereingtyUnionV1 to appease the leave voters), then everyone just leaves EUv1.
The rules mean they can't force Hungary out, but Hungary can't stop everyone else leaving and forming a better club.
Between the "pulp fiction" attributation and the nazi forehead story the other day, I think Putin has been on a QT film marathon recently.