Any children born to you after them will be yours; in the territory they inherit they will be reckoned under the names of their brothers.
NIV
But other sons who may be born after them shall be your own; and they shall be called after the names of these [two] brothers and reckoned as belonging to them [when they come] into their inheritance.
AMP
And thy issue, which thou begettest after them, shall be thine, and shall be called after the name of their brethren in their inheritance.
KJV