Normally you don't allow to change a username which I respect.
I tried to register on Treknature as "Praetzer" which didn't work.
After your clearance of the issue, I now registered under Preatzera.
This is not good as people who click @Treaknature on Preatzera Te or Tl will not find me.
Besides that, I prefer to have an identical username in TE, TL, TN