Wis. Stat. § 856.29
If the will of the decedent provides for a testamentary trust, the court shall appoint the trustee upon admission of the will to probate at the same time that letters are granted to the personal representative, unless the court otherwise directs. The trustee so appointed shall continue to be interested in the estate, and beneficiaries in the testamentary trust shall cease to be interested in the estate except under s. 851.21 (3). Letters of trust shall not be required to evidence the authority of a testamentary trustee and a certification of trust under s. 701.1013 shall be sufficient evidence of such authority. This section shall apply to wills admitted to informal probate and letters issued in informal administrations.
Wis. Stat. § 856.29
If a trust document allows beneficiaries to select a successor trustee but does not specifically allow appointment without court approval, the instrument should be read to permit nomination of a trustee subject to court approval. Matter of Sherman B. Smith Family Trust, 167 Wis. 2d 196, 482 N.W.2d 118 (Ct. App. 1992). A trustee has a duty to the trust beneficiaries to ensure that the personal representative transfers all property to which the trust is entitled. Even when the same person acts as trustee and personal representative the trustee has a duty to enforce claims the trust has against the personal representative. Old Republic Surety Co. v. Erlien, 190 Wis. 2d 400, 527 N.W.2d 389 (Ct. App. 1994).