By a will signed and attested as provided in this article a testator may devise and bequeath real and personal estate to a trustee of a trust which is evidenced by a written instrument in existence when the will is made and which is identified in the will, even though the trust is subject to amendment, modification, revocation or termination. Unless the will provides otherwise the estate so devised and bequeathed is governed by the terms and provisions of the instrument creating the trust including any amendments or modifications in writing made before or after the making of the will and before the death of the testator.
W.S. 2-6-103