§ 1013. Intervention by permission. Upon timely motion, any person may
be permitted to intervene in any action when a statute of the state
confers a right to intervene in the discretion of the court, or when the
person's claim or defense and the main action have a common question of
law or fact. In exercising its discretion, the court shall consider
whether the intervention will unduly delay the determination of the
action or prejudice the substantial rights of any party.