Zefi, I had to think about this a lot after reading it yesterday. I didn't want to just leap in with a bunch of "off the top of my head" opinions. It's too serious for that. It wouldn't be so bad if it were just Tana, but with Billy so tiny, it makes it a lot more scary. And just think what could happen if eventually it was a small child who got her pissed off. Scary stuff.
I've been having to teach Chula to share "me" with Poco. I've mentioned about her growling when the pups are too rowdy, and I do let her have her little growls if she's on the floor trying to sleep and they have decided to wrestle 2 inches from her nose. She doesn't move.... just lets out a rumble, and they move away.
But she didn't like it when she'd be laying under my feet when I'm sitting on the couch, or just sitting by me, and Poco would come up to say hello and get cuddles. Remember I was talking about the "claw hand" in the other thread? The moment she'd growl, I'd poke her with my claw hand and tell her NO very firmly. I bring Poco on up and cuddle him. I am the pack leader here and she does not get to decide who gets cuddles.
When we got Archie, a friend told us about The Dog Whisperer, Cesar Millan. She loaned me his book, and we started watching all the tv shows where he is rehabilitating dogs that are out of control. It's all VERY fascinating! He works from the basis of dogs being first Animal, then Dog, then the Breed of Dog, and THEN.. little "Fluffy" whom we love. He works in conjunction with the natural behavior of dogs. In the USA, we tend to treat our dogs like "part of the family" and completely forget that they ARE dogs. That they were originally wild animals and they all descended from wolves. They still have the pack mentality engrained in their genes, and the pack order is still there inside them.
So we got Archie last June as you recall. At first, I really wasn't sure of how I should handle his interaction with Chula. She's always been "my girl" and I had this feeling that she was "special" and should get special benefits because she's older and has been around longer. Archie was the newbie.. the interloper.. and I was all feeling sorry for Chula because she had to put up with this "annoying little shit" that we'd thrust into her life.
Well, letting her be "special" wasn't working too well! She was acting like Queen of the House, and it wasn't boding too well for little Archie. I kept watching the Dog Whisperer. And he really impressed me on the fact that when you have dogs in your life, there can not be a doggie pack leader. The pack leader must be ME! And if there are other humans around, then they also are pack leaders. NO dog can be OVER any person in the house. We are the pack leaders and ALL the dogs are our "pack".
When Pagan is laying with Greg like that and growling at anyone who is intruding.. she is CLAIMING HIM. She is being dominant and claiming him for her own. Like you said, "He's MINE!" This cannot be allowed. This is deadly dangerous. (you already know this, so I'm not trying to lecture you.. just thinking out loud...)
First of all, I don't think Pagan should have been allowed to even growl at the others when they came near Greg in the past. She should have been given a quiet command to knock it off. When Chula does this, she gets my curved fingers in a quick touch at the throat (claw hand) and a "SHH!". She stops and looks at me. I pet the puppy, and watch Chula. If she relaxes, I pet her too. If not, she gets more warnings, and when she finally relaxes, I pet her (still petting the puppy).
Okay, while I'm blathering on..

Throwing her into her crate was a good thing. You HAD to protect the others. And I'm so glad Greg was so quick and saved little Billy. Yay Greg! Good man!
What I would have done a little differently is this. If this were Chula, I would have flipped her ("rolled her") on her side immediately. Establish my dominance and place her into a submissive position. I actually had to do this with Chula a few weeks ago when she went after Poco too aggressively. To her embarrassment (lol), she found herself immediately on the floor, on her side, with my claw hand at her throat. Exactly like a pack leader would dominate a bad pack member. This didn't hurt her in any way. But it told her in no uncertain terms that I was in charge and she was NOT going to do that any more! I didn't allow her back up again until she relaxed and accepted the position. Then I stepped back and released her. She waited a moment, then got up, shook herself, and walked off. The pups found it all fascinating, but she ignored them completely. Poor girl.. so humiliated! LOL!
So I've really had to change my thinking. I adore my girl Chula. She's my "first love". But I can't allow her to think that she's in charge around here. I am.
I started to write more, as ideas for what to do to work with Pagan getting used to Greg loving on ALL the dogs, but I erased it. I'm no expert by any means, and I don't want to start throwing out advice! Opinions, sure

, but I'd better not start thinking I know it all!
But I would love to see you be able to read "Cesar's Way" by Cesar Millan. Can you get that in Tasmania? And if you have access to his shows ("The Dog Whisperer") then they are absolutely priceless! All this is also available on his website, his books and his shows are on DVD now too. His site is at
http://www.dogpsychologycenter.com/The only reason I'm saying so much, Zefi, is because I really hope you can find some way to deal with this. Please don't feel like I'm trying to tell you what to do! They are your dogs and I know you will do what you feel is best for you and your pups. I completely respect that, so please accept all this as only "my two cents".
Good luck!