The Pkhonor Forums have a feature that allows users to link their game accounts to their forums account. You can access this feature by entering your UCP (User Control Panel). To access the UCP, the user need just to locate the grey cog and click it. The cog looks like this.

Once the user is inside of the UCP, locate the section labeled Link another account. To link accounts to your forums account, you must have the username and password of the account.

Changing the name of an account on the forum is as simple as setting the displayed account. To access the list of accounts to select from, simply locate the User Control Panel section that is labeled Linked game accounts. Once you've found which account you want to be displayed, simply click the green arrow to make it the display name.