To my knowledge, the dead are not added to the rolls of the earthly church. If you are referring to the dead being baptized and confirmed into the mormon church by proxy, then that would be different.
Thus, faithful members of the kingdom of God on earth, while they are yet mortal, search out their dead ancestors and perform the ordinances of salvation and exaltation for them in the holy sanctuaries set apart for these purposes. Then, upon departing this life, those same faithful souls seek out and teach to their ancestors the saving truths of the everlasting gospel. And thus does the gospel continue to be preached among the dead. (Joseph F. Smith, Gospel Doctrine, Deseret Book Co., 1939, pp. 47276.)
Logic would have it that the membership numbers quoted by Salt Lake City would be much higher if they were counting al the millions of dead that have had proxy baptism performed in their names.
Question for the mormons. Do general authorities take their turn cleaning LDS chapels?