Lifesteal Ranks stack or replace?

[mrpiggysanta]

Hi

My son bought Emperor rank and likes that he gets a chest with some items every couple of days.

He wants to buy some of the other ranks too so that he can get chests for all the ranks

My question is, if he buys another rank will he still be able to collect the chest for emperor rank, plus whichever one he buys? Or will the next one he buys just replace the emperor rank and he won't have access to it anymore?

Thanks