In Ber. 49, Yaakov blessed his 12 sons in a particular order, at least based on the various notes to the Stone edition of the chumash -- he started with the sons of Leah (in a specific order) and then went to the maid servant's children (in a particular order though not purely by age, for example in pasuk 20) and then to Rachel's sons.
Before this, he raised up Ephraim and Menashe to the status of his children (48:6). But if they were of that status, why didn't they get blessed in the order along with the other brothers? And if they were not truly of that status (at least not yet) why did they deserve to be blessed before their elders, the sons of Yaakov? Shouldn't their blessing have come either with or after the sons?