Just for fun I changed my display name quickly...

it seamlessly transitioned at the top, going from Monarque to a different one.

If I were to change it to, say, Powerman5k, what would happen?

When I logged in, would I just have to...

Put in Powerman5k OR the registered email + the correct password...

Or, would I still need to put in Monarque?

Are there any limitations to this?

Bonus question: if I had registered on other instances using Monarque, would that affect my username over there..? Would I now have forked usernames...?