If a trustee determines that an allocation between principal and income required by Section 18, 19, 20, 21, or 24 of this act is insubstantial, the trustee may allocate the entire amount to principal unless one of the circumstances described in subsection C of Section 4 of this act applies to the allocation. This power may be exercised by a cotrustee in the circumstances described in subsection D of Section 4 of this act and may be released for the reasons and in the manner described in subsection E of Section 4 of this act. An allocation is presumed to be insubstantial if:
Okla. Stat. tit. 60, § 175.408