This is not a legal document. OK, so if all your family agree, and all are over 18 or not under a disability, they can come to whatever agreement they wish regarding your estate. However, unless the letter is signed by you in the presence of at least 2 witnesses and they then attest and sign the document, it is not legally binding as a Will and your estate will pass under the intestacy rules if the family cannot agree. This is correct for England and Wales, I am not sure about Scotland, but seem to think only one witness is required.