Yes, a member may designate a trust as beneficiary under the various MMBBB Plans. If the trust is irrevocable upon your death a Tax Identification Number (TIN) is required on the W-9 form. If the trust is revocable upon your death, and your spouse is a trustee with the power to revoke the trust, their Social Security Number can be submitted on the W-9.
As far as naming a child, MMBB and the guardian determine the method of payment that would be most beneficial to the child until age 21. Then the child determines how they are to receive payments. The guardian can request a complete settlement at any time prior to the child turning age 21.