If an O&G lease omitted/forgot a deceased child's children, thus dividing the lease by 5 instead of 6, is that a mistake, or should the deceased child's children receive one share of the division?  This parcel of land is one acre.

Father/Mother owned one acre.  Five children from marriage.  Never divorced.

One child (divorced), dies, leaving four heirs.  All heirs of deceased child are grown/married (over 23) and their father is deceased.

Father died owning one mineral acre; divided 1/3 surviving mother, 2/3 children. (didn't know about owning mineral acre until lease was mailed to them with those divisions).  Parcel of land was sold to one heir by mother after fathers death, but minerals reserved.

The lease only includes the four surviving children and mother.  The deceased child lived/died in Louisiana, and the (4) children from that marriage live in different states, none in Arkansas.

What should they do, some have already signed and received bonus $; no one noticed the omission until now.  Two heirs haven't signed yet.