Provision in deed. Grantors make this conveyance as an advancement to grantee, and hereby value the lands at the sum of $_____ per acre. If, upon a final settlement of the estate of grantors among their children, there is not sufficient property to make the share of each child equal in value with the property hereby conveyed, at the value set upon it in this deed, then a lien is hereby retained on the land to secure to the other child or children of grantors in any sum necessary to make them equal with grantee.