A plaintiff may assert a claim against a thirdparty defendant within twenty days after service on him of a copy of the third-party petition. Thereafter he must obtain leave of court.
A third-party defendant may assert a claim against the plaintiff within twenty days after he has been served with a third-party petition. Thereafter he must obtain leave of court.
A party shall serve his reply to a counterclaim in an answer to a third-party petition or in an answer to a cross-claim within twenty days after service of the pleading containing the counterclaim.
Okla. Stat. tit. 12, § 4.1