"the Trust document states that 4 Beneficiaries have equal 25% shares."
From what you posted, I'm not sure that it says that:
"The Trustee shall immediately distribute all amounts withdrawn to: to my descendants, per stirpes, who are beneficiaries of this trust; and if no descendant of mine is a trust beneficiary, then to the trust's Income Beneficiaries in equal shares."
Of course if there 4 descendants who are beneficiaries under the trust, per stirpes, or there no descendants who are beneficiaries under the trust but there are 4 (non-descendant) income beneficiaries, your statement that there are 4 beneficiaries would be true. What you posted does not seem to indicate whether descendant beneficiaries under the trust are equal beneficiaries.
The trust language you posted seems to suggest that the trust is not permitted to allocate shares of the inherited IRA out of the trust as inherited IRAs for the benefit of the trust beneficiaries but instead seems to say that the trust must be the entity that takes distributions.
These are all things that you should review with a competent trust attorney.
