Very dominant!

Find a professional dog behaviorist. This issue is too big to be getting tips from a dog forum.

You need one on one help, somebody that can explain to you what to look for exactly and follow up with you to see if you are applying it correctly.

The professional behaviorist can even help you to diagnose correctly the issue, not because your dog is aggressive that means she is dominant. Puppies at 6 weeks old are not looking to be dominant and even less towards their own mother.

 Have you had her thoroughly checked out by a vet to rule out a medical problem?  Gotten an full thyroid panal?  A six week old puppy attacking its own mother sounds to me like something might very well be wired wrong.  I also don't see her as much of a dominant dog if they other dogs are easily whipping her butt in a fight.  Is there any bloodshed in these fights?

I aggree with getting a professional in to help you with the situation.

http://www.apdt.com.au/files/dominancestatement.pdf

Another member posted this article which you might find interesting.  I do agree that the problem needs to be assessed by a professional, in your home. 

http://www.iaabc.org/  This is a good place to start your search for help.  After the Vet check to rule out medical issues.  I had a good article on what to ask someone when looking for a behaviorist but will have to look for it.  Good luck.  That sounds like a terrible situation for everyone.  I hope you find some help.

 Don't confuse "aggression"with "dominance". There are many kinds of aggression.  Yes to a FULL vet exam and yes to a reputable, certified behaviourist.  I hope you can work out is wrong and help this poor dog.

Can you expound on "fight" and "attack"?  Like is she actually biting (latching on and ripping/shaking) and drawing blood?  I ask b/c I just got back from a 2 week vacation which included my three dogs and my cousin's dog.  My three dogs are quite used to being in a "pack" and have had lots of exposure to other dogs.  My cousin's dog, however, is pretty much the most reactive dog I have ever met.  Anytime my dogs would come inside she would fly at them, barking, snapping, growling.  She would run straight at them, or would even chase them and nip at them as they turned and walked away to avoid her.  However I wouldn't say she was "attacking" because she kind of just hovered underfoot, barking, spitting, and body-blocking them but wasn't actually biting or trying to kill them.  Not that it's any better/worse, but I think it does have implications as far as what is going on and how it is "treated".  Basically I would call my cousin's dog a super-reactive dog, not necessarily a dog-aggressive dog.  Like your dog, nothing we did deterred her fits, she was basically flying into these reactive rages for two weeks straight and likely would have continued if we'd been there longer.  Luckily, my dogs did not even feel this dog was worth correcting so they would just turn and walk away or jump on a couch to avoid her.

 If you don't want to identify them by name, you can use initials.  Would you tell me the ages and genders of each dog?  Also, when did you get them, at what age, and are any of them related, and how.  How much training has each dog had?  Are the fights over any particular thing that you can identify, such as food, space, sleeping spot, etc.?  Do any of them draw blood when they fight and which ones? 

And, please stop the squirting and swatting - it clearly isn't working anyway, and I find that aggression from the owner usually tells the dogs that you are joining in, or that you are as panicked as some of them are.  Leaders are quiet and purposeful.  Your Boxer may actually be the more powerful dog if he does not join in - after all, he doesn't have to bluster, he could squish her in a second if he really needed to.  Perhaps he's just waiting for the results of the "b*(&^ fight."  For now, separate the female Boston from the other dogs.  You may have a situation that is not easily resolvable without professional help, and even then... So, don't wait until a dog gets really damaged.  Your fighter may just be happier and better off in a single dog household if you can find someone to take her.  If this dog is not spayed, she should be.  It will not likely help with the aggression, but if she was aggressive even as a pup, that isn't a temperament I would want to risk breeding for.