By default csmig assigns all orphan calendars to a single owner, but I would like to assign different owners for some orphan calendars.
csmig does not accept the mapping file in the command line. However, you can assign owners to the orphan calendars in the original database before the migration. Check the dry run mapping file for all orphan calendars. Then use the cscal utility to assign owners to the orphan calendars before the migration. Run csmig in -dryrun mode again to verify the new owners.