I do not believe that Delila (as spelled on her tombstone) was the daughter of Isaac. I think she was the daughter of Jacob, Isaac's brother, and his wife, Mary Halleck. Delila named her first two children Jacob and Mary. Delila and James Lawson left Rush,IN for Clark,IL the same year as John Halleck Partlow (whom I believe is Delila's brother). They are living near each other in the 1840 census. They most likely went together.
Delila's and James B.'s son, Robert Bradley Lawson, is my gr gr grandfather.