§ 1511. Additional parties. 1. In an action brought under this
article, the person in possession shall be made a party to the action,
and when such person claims the right of possession, or an interest in
the real property, under another, such other person shall also be made a
party.

2. Where it appears to the court that a person not a party to the
action may have an estate or interest in the real property which may in
any manner be affected by the judgment, the court, upon application of
such person, or of any party to the action, or on its own motion, may
direct that such person be made a party.