According to a discourse given by George A. Smith given on Dec. 25, 1874, in St. George, Utah; in St. George Stake, General Minutes, vol. 4, Church Archives, he related the following:
Some of the Twelve asked Joseph if there could not be some shorter method of administering for so many. Joseph in effect replied: ‘The laws of the Lord are immutable; we must act in perfect compliance with what is revealed to us. We need not expect to do this vast work for the dead in a short time.’Joseph Smith also taught the following:
When any of you are baptized for your dead, let there be a recorder, and let him be eye-witness of your baptisms; let him hear with his ears, that he may testify of a truth, saith the Lord; that in all your recordings it may be recorded in heaven. … And again, let all the records be had in order, that they may be put in the archives of my holy temple, to be held in remembrance from generation to generation. (D&C 127:6–7, 9).In other words, we need to do the work carefully and not in haste.
In the early days of The Church of Jesus Christ of Latter-day Saints the members were taught by Joseph Smith that they were to do proxy work for their "kindred dead." See Teachings of Presidents of the Church: Joseph Smith, (2011), 468–478, Chapter 41, Becoming Saviors on Mount Zion.
So, who are our kindred dead?
As a genealogist, I would define kindred dead as those with whom we have a blood relationship. However, in doing research, I am certainly not limited by that requirement. I can do research about anyone, even someone to whom I am not related. However, from time to time, the instructions from the Church concerning those who we should include in doing our family's ordinances has been adjusted from time to time. But the basic idea still focuses on blood relations.
The current policy is set forth on FamilySearch.org in the Help Center article entitled, "Individuals for whom I can request temple ordinances." The policies have changed somewhat from time to time, but essentially always focused on relationships. No matter how you read the rules or any changes, the rules have never allowed people to submit ordinances for those to whom they are not related.