Relationships between multihoming and renumbering

a site being renumbered is also a multihomed site.

what should the site do when a new prefix is assigned?
update DNS entries
stop advertising old prefix(es) via RA
and more?

what should the site do when the old prefix becomes deprecated?
new prefix(es) will be used for actively opened connections.
what for passively openned connections?
accept? reject?
relationship with remaining DNS cache entry?