I have a quandary for you all. 

So I've been re-reading the Animorphs books the past few days (what better thing to do when you're laid up sick?!) and something struck me. Yeerk names seem to reflect their rank, with Temrash 114 mentioning he had just moved into the 100s. This seems to imply that Yeerks change their name as they move up, and thus when one member moves up, everyone now below moves down. 

Then I got to thinking. Visser Three is named Esplin 9466. We learn this in the Hork-Bajir Chronicles, written quite a time after The Capture, in which Temrash mentions his promotion. Even after his promotion to Sub-Visser Twelve, Esplin 9466 still refers to his name as separate. 

This is the question, how do Yeerks rank themselves? Do you think they retain their final names and numbers once they reach the Sub-Visser/Visser ranks? Or is Visser Three just a sentimentalist and Yeerk names are synonymous with their ranks?