Set up rank children

Hi everyone, im traying to set up one of many children rank. My parent has a lot of children, and someone will be deastroy, and repeat add, but rank is still changing throught this process. How can i set up fixed rank for one children ("GameObject") - for this child i need fixed rank.

for better understandig look at these pictures: Correct - this is what im trying to do :

and this is Incorrect, after a few changes :

So if u know solution, pls help me :) Thanks Thomas