20 Pa.C.S. § 7740.5: Reformation to correct mistakes - UTC 415.

The court may reform the terms of a trust, even if unambiguous, to conform to the settlor's probable intention if it is proved by clear and convincing evidence that both the settlor's intent and the terms of the trust were affected by a mistake of fact or law, whether in expression or inducement. The court may provide that the modification have retroactive effect.