You stated in an earlier post that you received an 1099-INT and 1099-DIV from the investment firm.
Did you also receive a K-1? I suspect not so that would be left to you, as trustee, to determine what has to be distributed per the trust document. Typically, you would make a final distribution to the beneficiaries which would include all of the income and assets of the trust (in this instance split three ways).
