An alternative is to write a letter to a friend or relative stating that upon the death of the pet owner, the animal should be euthanized. A letter of instruction is a cheat sheet for anyone involved in settling your affairs.Unlike a will, this letter has no legal authority. You will have to file the will in the probate court in the county where he resided at the time of death and apply to be appointed executor. A letter of instruction is something you write to tell your personal representative (also called an executor) what to do. A letter of instruction is a document that lists all relevant financial information that your family members or executor need if something happens to you. A letter of last instruction is a document that allows you to organize and give your family instructions pertaining to your final wishes. A letter of instruction can complement an estate plan and provide your loved ones with additional details about your assets and wishes after death. The provisions of this instruction apply to all personnel who visit, live or work on Travis AFB. This guide tells you how to use a Small Estate Affidavit to probate an estate in Texas.