Torah T'mimah there 17
Quoting TB Bava Batra 123a
When did Yaakov choose Yosef to be the Bechor?
Is it Vaychi 48:5 when Yaakov said "KiR'uven v'Shimon yihyeh lee"
Vaychi 48:22 "shchem echad al achecha"?
Note: Both implying pee sh'nayim...
Vayeishev - when Yaakov gave Yosef the K'tonet Passim; which implied that Yosef now held the mantle of "B'chor"?
BE"H we will cover Vaychi next and reflect back to Vayeishev and Vayishlach later.
Note: Stay tuned for "surprise twist ending"