Upon or before the return date any beneficiary of the trust may file the beneficiary's written objections or exceptions to the account filed or to any action of the trustee or trustees set forth in the account. The court shall appoint guardians ad litem as provided in RCW
11.96A.160 and the court may allow representatives to be appointed under RCW
11.96A.120 or
11.96A.250 to represent the persons listed in those sections.