'Firstborn Son' in the Bible

If a man have two wives, one beloved, and another hated, and they have born him children, both the beloved and the hated; and if the firstborn son be hers that was hated:

[nevertheless] {it will be the case that} on the day of bestowing his inheritance upon his sons, he will not be allowed to treat as [the] firstborn son the son of the beloved [wife] {in preference to} the son of the disliked [wife], [who is] the firstborn [son].

But he shall acknowledge the firstborn son of the disliked [wife] {by giving} him a double portion of {all that he has}, for he [is] the firstfruit of his vigor; to him [is] the legal claim of the birthright.

It shall be that her firstborn [son] will be given the name of the dead brother, so that his name will not be blotted out of Israel.