Lehi the prophet in the Book of Mormon was of Ephraim. But his friend, Ishmael, whom he brought to the Americas was of Manasseh. Lehi’s sons married Ishmael’s daughters. The people of the Americas today are of
Manasseh. Those who are Anglo mostly are of the tribe of Ephraim when we receive our patriarchal blessings. So, you are correct. Both are of the lost tribe of Joseph who would lead in these last days.
As Paul wrote in Hebrews, there are 2 orders of the Priesthood. The order of Melchizedek and the order of Aaron (Levitical). Melchizedek is the higher order of inward ordinances. Aaron is the lower order of outward ordinances. Jesus gave these to Peter, James and John and John the Baptist. They came and gave these two orders to Joseph Smith and Oliver Cowdery in 1829. From them, these orders are conferred upon men from generation to generation to the present. This was done by Paul with the generations in his days until the authority was lost due to apostasy. As I did, you may study and pray about this and find out for yourself.