Will LL accept DMCA notices filed on behalf of other residents?

So I guess I have an unusual question.

The other day someone showed me a vendor kit for sale at a mall. The vendor was advertised as a do-it-yourself-kit that you simply rez and it comes with 14 weapons with copy/transfer permissions that you can resell yourself. All 14 weapons were freebie items created by other residents.

I contacted first the eleven different residents whose items were being resold to give them the heads up and ask them if they knew about it and were okay with it. None of them were. In several instances the weapons were using open-sourced scripts not even licensed for sale by the original creators. I then contacted both the owner and the creator of the vendor to let them know that they were selling and redistributing items with freebie content not authorized by their makers. The owner of the vendor took it down immediately when he found out about the "stolen" content, and after I got in touch with the person listed as the creator, he was very upset about it because he said he's never made a vendor script before. As all of the items in the vendor except for the texture were freebies, it's pretty likely that someone got a full permission prim he made and built a box out of it.

He contacted a Linden who told him that a DMCA notice had to be filed for LL to trace both who made the vendor originally and who made the texture, since it's being distributed with this guy's name on it. Side question, why is this necessary? If you have the potential to find this information out shouldn't you just do it, rather than wait for it to become a legal situation?

Anyway, since I didn't make any of the weapons in the box, this comes to my point. I contacted all of the creators and offered to "deal" with it for them; they all unanimously told me to go ahead with it and they gave me permission to file whatever legal notices I need to file. Will LL accept these, however? If I'm given authorization by another resident to handle it on their behalf, will LL honor it as long as they've given me permission? And if that's the case how do I go about filing one? Do I need to file eleven different notices, or will one that lists all eleven people be sufficient? And since the guy already took down the vendor and the "creator" is very upset about the item being masqueraded around as his, is this actually necessary to get Linden action? Since all parties involved want to find out the actual creator and there isn't any disagreement, I'm wondering if it's completely necessary to elevate the issue when there isn't a debate.

Thanks a lot for the help.

PS: Oh, I forgot to say, in a few cases the weapons in the kit were incomplete versions that the makers assured me weren't even made freely public, much less put out anywhere, and they were very, very unnerved that they made their way out of their inventories and into this box.

The DMCA process is described here.. You could conceivably file for others (see #6 in the process -- you must be the copyright owner or authorized to act on behalf of the owner). You would need to be certain that they are in fact the copyright owners, as there are penalties for making false claims, as described on that same page.