introduction difficulties

Question
I have 4 female mice, I bought them 3 days ago. Originally I started off with three but two of them were always huddled together and the third one was constantly on its own.
so I bought one more hoping that the lonely one would socialize more. But it started chasing after the new one over and over again and took quite a few chunks out of its ear, it has been fairly aggressive after that and very protective over the two other females.
So I separated that one from the the new one and two females but the two other females were attacking it also. So I bought 3 cages, put the aggressive mouse in one, the new one in another and the two females in the third. I know its only been three days and I probably should wait longer for them to get used to the situation they are in but I am just wondering whether I have done the right thing. Please could you help me?

Answer
Dear Carolynn,

Do I have this right?  (Put their names in for this to make sense!):

Mice A, B, & C were living together.  
Mice A & B were ignoring Mouse C.  
You introduced Mouse D.  
Mouse C chased Mouse D and bit her ear, and was protective of Mouse A & Mouse B.  
You took Mouse C out.
Mouse A & Mouse B attacked Mouse D as well (Did they draw blood?)
Now Mouse A & B are living together and C & D each live alone.

I have a guess.  Did you put the mice in a new, clean cage before introducing them, or did you put Mouse D in the inhabited cage with the other mice?  If the cage was not fresh then Mouse D had a big disadvantage.  

My advice is the following.  Put Mouse A *or* B in the cage that Mouse D has been living in for a few days (to give her an advantage).  Put a tiny dab of REAL vanilla essence on the base of their tails and chins.  This way they will smell the same.  Watch to see what happens.  Lots of chasing and squeaking is totally ok.  It's just not ok if one is bleeding.  The other Mouse B/A can go with Mouse C.  

If this works you will at least have two happy cages.

If it doesn't, switch Mouse A & B and try again.

If you like, you can then try putting them all together after that; once again, use the cage that Mouse D has been living in.  However, blood and chunks out of ears is not ok.  If they stay in separate cages, keep the cages close together so they can communicate by sound (high-pitched squeaks that we can't hear).  

best of luck!

squeaks,

Natasha