On page 409 where the Borrower is posted back during an Edit. I just wanted to know why it was necessary to Remove the existingBorrower before calling UpdateMe and then Adding it back into the LoanApplication.

app.Borrowers.Remove(existingBorrower);
existingBorrower.UpdateMe(b);
app.Borrowers.Add(existingBorrower);
_repository.Save(app);

Thanks!