How I make a joint account in envato?

I am an envato author. I want to make it as a joint account. But envato user id is changeable. How could i make a legal partnership account in envato. Any suggestion please.

Even if the username changes, the username change will be visible at the author page so you can ignore this part. My suggestion, ask the author send an email via the system and keep the email. In case of any problem, you can contact Envato for DMCA.