Hello! Just thought I'd give in my input to this!
I definitely agree that there should be a pirate-themed event, but as for the prefix/package, I also don't believe that it would fit with Potterworld right now. From a roleplay perspective, it would be hard to incorporate something that wouldn't fit with our current "theme," per se, and I think that it could collide with the current RP. From an unofficial RP POV, it's possible, but would again be hard to incorporate. From an official POV, it would definitely be much harder than the other allegiances, because of the following reasons:
1) There wouldn't be an obvious "leader" or "inner-circle members".
2) Pirates aren't as obvious in the HP fandom as things like Werewolves or the three allegiances.
3) It wouldn't really fit with the current storyline.
In my opinion, it shouldn't be added as a club/allegiance, but rather an event like mentioned previously!