A revocable trust may be amended by a written statement disposing of items of tangible personal property not otherwise specifically disposed of by the settlor’s will or the trust instrument, other than money, coin collections, and property used in a trade or business. To be effective as an amendment, the writing must be referred to in the trust instrument, must either be in the handwriting of the settlor or signed by the settlor, and must describe the items and the beneficiaries with reasonable certainty. The writing may be referred to as one to be in existence at the time of the settlor’s death; it may be prepared before or after the execution of the trust instrument; it may be altered by the settlor after its preparation; and it may be a writing which has no significance apart from its effect upon the dispositions made by the trust instrument. A writing may include multiple writings and if an item of tangible personal property is disposed of to different persons by different writings, the most recent writing controls the disposition of the item.