Sample: Letter of Wishes to Trustees. Below is a sample letter of wishes that can be sent to the trustees or to the administrators of your.A letter of instruction works alongside your will to share your wishes in plain terms. Include their name, address, telephone number, and email address (This should be kept up to-date). Include family members, acquaintances, and organizations. A letter of instruction is an estate planning tool that can be very helpful in the administration of your estate. A letter of instruction is an informal document in your estate planning toolkit. 29 Unique Letter Greetings to Make a Lasting Impression. Greetings! The letter of instruction is designed to address these types of practical, day-to- day questions your representatives might face. (3) Do not use letterhead as personal stationery.