When you complete all the quests for a particular 'questmaster', such as the Wizard, there's a button that says 'Other Quests'. When you click on it, it brings up other quests. However, I noticed Drink Carl's Quests were not listed on the bar, even though Drunk Carl also has a Quest Shop. Every other questmaster with a Quest Shop is also currently featured in the 'Other Quests' bar. Why not Drunk Carl?

http://subeta.net/forums.php/read/817471/See-Other-Quest-Links

subeta.net/forums.php/read/816545/add-carl-to-the-top-bar-on-the-see-other-quests

+probably more threads

As much as this gets suggested I would just like for them to do it and get it over with.