As Jacob’s life comes to a close, it looks like there is going to be no other opportunity for direct communication with Elohim. God told Jacob to go to Egypt in chapter 46, and that seems to be the last communication from God until he speaks to Moses 400 years later.
Elohim has been with the family since Abraham’s father left Ur for Canaan, and we assume he was the household God of Terah’s descendants before that.
When Jacob passes away, the covenant made Elohim to Abraham, Isaac, and Jacob will only live in tradition. Joseph can interpret dreams, however, he has not interacted directly with Elohim.
By placing Ephraim, Joseph’s younger son, ahead of Manasseh, Jacob establishes that they thread of Elohim’s covenant will be passed to Ephraim’s descendants.