(a) If a particular trustee is a beneficiary of the trust and conversion or failure to convert would enhance or diminish the beneficial interest of the trustee, or if possession or exercise of the conversion power by a particular trustee would alone cause any individual to be treated as owner of a part of the trust for income tax purposes or cause a part of the trust to be included in the gross estate of any individual for estate tax purposes, then the particular trustee may not participate as a trustee in the exercise of the conversion power except that the particular trustee may petition the court under subsection (a) of Section 1104 to order conversion in accordance with this Article.
     (b) If the particular trustee has one or more co-trustees to whom subsection (a) does not apply, the co-trustee or co-trustees may convert the trust to a total return trust in accordance with this Article.