Charles Ellicott Commentary 2 Samuel 14:7

"And, behold, the whole family is risen against thy handmaid, and they say, Deliver him that smote his brother, that we may kill him for the life of his brother whom he slew, and so destroy the heir also. Thus will they quench my coal which is left, and will leave to my husband neither name nor remainder upon the face of the earth." — 2 Samuel 14:7 (ASV)

We will destroy the heir also. —The woman puts this into the mouth of the family, because this would be the result of what they proposed. The effect of the parable is greatly heightened by this, and a covert allusion to Absalom as the heir of David is undoubtedly intended.