In the case of a restore where the backups were done from the global zone, the global administrator or a user granted the appropriate authorizations can reinstall the affected zones and then restore that zone's files. Note that this assumes the following:
The zone being restored has the same configuration as it did when the backup was done.
The global zone has not been updated between the time when the backup was done and the time when the zone is restored.
Otherwise, the restore could overwrite some files that should be merged by hand.