Dominance?

Question
I have three dogs. My 9 year old Japanese Chin male is a dear and we do pet assisited therapy at the local hospital.  My two girls are both Shih Tzus. One is 7 and the other 1 1/2 years old. They are fine with people but not with other dogs.  I took the young one in as a rescue and I assumed that the three dogs would work out their dominance issues.  This has not happened!  After several months the two girls are still fighting.  It has gotten to the point where someone is going to get hurt. They have been to obediance class.  Any suggestions?

Answer
If I were you, I would have a trainer come to your home to work with them.  I've had to do this before.  It does work wonders as they can see the situation first hand and be better able to tell you how to correct the issue.  Until then, I would figure out which one is normally starting the fights.  Then watch them to figure out what normally causes it.  Once you figure out if there is a certain thing that one or the other does that causes the fight you will better be able to stop it before it happens.  When they fight, I would seperate them with a very firm OFF!  It may take some time to correct the problem.