Considering that most of us (from cannot unsee) only got into Hetalia this last year, no, we weren't aware that anyone else had "claimed" the idea of a PJ party for themselves. If the people who ran it however many years ago have decided not to do it again, that should not prevent someone else from running a PJ party for that series if they choose to. Regardless of who did what whatever years prior to this coming year, if that person isn't planning to run one of the same name again, the fact that they did it before (whether we were aware of that or not) shouldn't prevent a new person from stepping up and holding something of the same name in a new year, especially if we're not "making it exactly the same".
We want to cosplay as Hetalia characters in our PJs. We're no longer holding the congress dance, so we now have time to host another panel. Someone we know IRL randomly suggested "why don't you do a Hetalia PJ party, since you and Rei have Den and Sve PJs?" We liked the idea, so we decided to do it. If someone was already planning to host the panel for 2012, we would have no problem saying "okay, good luck. we'll be happy to attend it". So far, I have not seen any mention of someone hosting it this year besides what we have decided to do, and by your own quotes, they don't seem to have any plans to do it because they are "all partied out".
We still plan to hold our PJ party, and if those who hosted it want to speak with us about it, they can. I don't believe it's a very pleasant thing to do, to deprive our congoers of the opportunity to attend such a panel just because the previous hosts of a similar panel have abandoned it, but don't want anyone else to host one because it's their "baby." Panels are panels. Our "PJ Party" isn't likely to be the same as any that were hosted before, simply because it's hosted by different people. We never went to the ones that were held before because we weren't part of the Hetalia fandom at that time. Now we are, and we will host the panels we choose to host, despite what anyone says about how we shouldn't because of one reason or another.
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@cosplaygeek4, turbosaiyanjason, cutthroatpixie: I'll put you up as attendees for the PG-13 panel. Thank you for your interest.