How do I add rich usernames to this?

[Tristan10]

How do I edit this code to allow rich usernames? I have used other resources to single out this line of code, but this uses a different method to generate the username.

<a href="{xen:link members, $thread.lastPostInfo}">{$thread.lastPostInfo.username}</a>

 

[Amaury]

@Liam W has an add-on that applies rich usernames globally.