Bekhorot 52: three things to remember

A firstborn receives a double portion only from his father's existing estate, excluding post-mortem growth like ripening grain or uncollected loans.
Dividing brothers act like buyers who must redistribute their inherited ancestral fields at Jubilee, though the firstborn retains his double portion.
A husband inheriting his wife's ancestral burial ground must return it to her family for money to prevent family disgrace.