The fact that you could not get a candidate for the third position within the same salary range suggests that people with the knowledge and skills required for the said position are not easy to find for the same salary. It shows that the third position is not same as the other two and is different and quires different talent. Also find out the levels of accountability and risk are higher for the third position. If so, you can defend higher salary for the third position on this count too also tell them like any other market the employment market too is subject to demand and supply principle and the value of a role goes up if people with the required skills are scarce.
B.Saikumar 10th September 2016 From India, Mumbai