I am happy to inform you that your son, Elder McKinney, has been called by the Lord to serve as a trainer of a new missionary, Elder Koo. I am confident that in this assignment he will use and further develop his leadership abilities.
This is the most important calling in the mission because he will influence the outcome of this new missionary's mission. As he properly trains, he will instill characteristics of teaching effectively, budgeting time and funds wisely, and working spiritually with investigators in the mission. In doing these things he will become one of the most important people in this new missionary’s mission experiences.
You may be well pleased with his progress as a missionary. I am sure you will see in him many good changes and much positive development. He is a great missionary! Please continue to give him your encouragement to magnify his calling as a proselyting missionary and as a trainer also.