No selective aggression allowed

Question
Hi, I currently have four dogs. A 10 year old female lab, very arthritic with hip dysplasia (but has always been the Alfa), a 5 year old male golden retriever, a 2.5 year old female Irish setter and a 5 month old female golden puppy. Until recently, the hierarchy was clear. The old lab ruled the roost.
The male golden was the Beta and the setter the baby of the pack(the golden pup just arrived).
The setter has always played a strange mouthing game with the Lab (like a puppy plays with a mother)and the Lab has let her do so till she would get fed up and let out a low growl. The setter would then get the message and scamper away.A month ago the same thing happened but when the Lab let out her growl, the setter decided to attack her and in a split second it was a full on fight. With one disadvantage. The lab because of her legs couldn't get up and as a result was dragged by her ears for a few feet . I had to get in the middle and force open the setters jaws to let go. I suppose this was the challenge for the Alfa place. Now everytime the lab comes very close to the setter, the setter lets out a growl. If I'm cuddling the lab, the setter gets in between and pushes her out and if the lab won't move, comes another growl.However, she does not try this with the male golden Ok, sorry about the lengthy background but here are my questions
1. Since the Lab lost the physical round, has the Alfa status changed ?
2. Should i continue to treat the Lab as the Alfa?
3. Can the setter attack again when I'm not around?
Another piece of information.I'm clearly Alfa to all and a calm "i saw what you did" is enough to get them to freeze.
please help !

Answer
Hi Nita, You need to be the alpha or pack leader and the dogs are all equal. You must make it clear that there will be absolutely no aggression or assertive behavior allowed within you pack, even when you are not around. Walking them all together at the heel, slightly behind your knee will help them understand your leadership. Even if your old gal cannot make it too far, a short walk as a group for her, return her home, and then continue on with the rest of the dogs. The rule must be get along or go in your crate. With our herd of horses, we say "get along or get gone". With the dogs, you cannot send them into another paddock, but you can send them into their crate. Proper crate training is creating a safe den for the dog to go with the door left open most of the time. So it is never used as discipline. But if aggression occurs, even a growl, we make everyone go to their den to cool off. "You to bed", You to bed"...all the way down the line until everyone is calm. Working at this will help for quite awhile. Please leave me some feedback and let me know how you progress. Warm Regards, Susan