Customer name in the email welcome.


I use the plugin Pro integrated sites with WHMCS.
WHMCS creates a random user name.
In WordPress Network settings email welcome to new sites using the USERNAME variable.

I would like to replace the USERNAME variable with the actual name of the customer.
What would be the variable to display the actual name of the customer?
Where can I get a variable list that I can use in e-mail welcome the network?

Thank you!