Introducing two female dogs

Question
Hello, My question is how should my Dad and I introduce, the right way, our two dogs that are already in the same house but still separated from each other.  We have sorta tried to introduce probably the wrong way before and my Pit Bull Chasity became aggressive toward my fathers dog named Anna.  
First time we tried to introduce them we had them on leashes. I have heard this triggers more aggression towards one another.  Second time we tried to introduce them we put a muzzle on the pit bull Chasity because the first time Chasity bit Anna. Putting the muzzle on Chasity didn't help and she tried to get the muzzle off and then tried to bite Anna again and so we seperated them again. Later I found its not good to muzzle them in that it causes more aggression. Help!!!
The German Shepard Anna we have had close to 10 years. She is kinda old, ornery. My Dad is worried she is gonna get hurt in this which doesn't help.  She gets along with a few other dogs, a few in the neighborhood and she plays with them okay and she gets along with my Grandmothers schnauzer who is also about ten years old.  
On to the pit bull puppy, around two years old.  I have had her about a year and a half, I have seen her get along with multiple other dogs but has always met them while off the leash and I think they have all been smaller than her and or male.
I moved back in at my parents house, the Pit Bulls mine, the German Shepard is my Dads. I don't want them to fight, they need to get along while I live here so we can all be at peace.  Should we introduce not on leashes? Should we introduce in fences, so they can smell each other? PLEASE HELP SOLVE OUR LIVING CONDITIONS. Thanks,
Katie Fletcher  

Answer
I doubt if you can get them to get along.  When two females who are socially mature decide to dislike one another, it is no small matter.  Leashes, when tight, can cause an insecure dog to feel aggressive.  But, what I think you have here is a female Pit who has decided not to like other females, and that can be deadly.  It is unfair to a ten year old dog who has been in her home that length of time to bring in a dangerous dog who could literally kill her.  Pit Bulls are often lovely with people, and your dog may be ok with males, but she is clearly not ok with this female Shepherd.  The problem is that even if the Shepherd were at fault in instigating the disagreements, a Pit will often not just nip and go about her business, she'll finish the matter.  If when she bit Anna, she broke skin, it is dangerous. Males often fight ritualistically, but females who detest one another may actually fight to the death.  So, you may have to separate these two indefinitely and not let them come into contact with each other.  If I were you, I'd find other living arrangements, because my gut feeling is that this is not going to work out well.
You should not attempt to introduce them again without professional help, and by that I mean a veterinarian or Ph.D. level behaviorist.

Thank you for the nice evaluation, even though my advice wasn't what you expected.  I always err on the side of caution, and so I cannot in good conscience say that I think this will be ok, given that one dog is damaging another.  Usually, if dogs are just jockeying for position, they might fight a couple of times and be done with it, most often with no damage to one another.  But, if the dogs are basically the same status and it's escalating, or are from a typically dog aggressive breed (even though they love people) that's a danger signal.  Because I cannot see this first hand, I would never want to give you hope, only to have you make a serious error by continuing to place them in harm's way.  That's why I think the vet evaluation and help from a pro are essential.  Good luck to you, I hope everyone stays safe.