mailing-lists-sieve can act as list exit in Listserv and upload the list' scripts when a subscriber joins or leaves a mailing list, or is added or removed. To achieve this, create a symbolic link from /home/listserv/home/MAILING_LISTS_SIEVE to the actual mailing-lists-sieve , create a configuration file for mailing-lists-sieve in /home/listserv/.mailing-lists-sieve (or a global one), add to listserv's LIST_EXIT option MAILING_LISTS_SIEVE and eventually add to the configuration of each mailing list Exit = MAILING_LISTS_SIEVE.
Listserv does not offer a list exit, that is invoked, when the list configuration changes. In cases where Send is changed from Private to Public, or new Editors are added, the site administrator is supposed to upload the scripts manually by invoking mailing-lists-sieve listname