Bava Batra 31: Changing One's Claim in Court

The rabbis use a particular case to explain a number of competing and complimentary concepts.  In a nutshell, the case states that two people claim that property belongs to them as it belonged to their ancestors.  

If one of the parties uses the argument of chazaka, he wins the claim because of the concept of migo, when a person could have claimed something more advantageous but instead raises a potentially damaging but still relevant argument, he will win his claim. He could have claimed that he bought the land from the claimant and thus has chazaka, but he claimed rights to the land through inheritance.  If witnesses contradict his claim to inheritance, though, the judge cannot rule in his favour.  

The rabbis consider whether or not it is acceptable to modify one's statement slightly - is it alright to argue a slightly different point in court after one's first claim has been made?  Is it alright to state that the inheritance argument was added because the land was purchased from the claimant long ago?  The rabbis are concerned about many possible issues: learning lies and bringing them to court, contradicting oneself in court, claiming something new outside of court, with witnesses, etc. 

The Gemara considers witnesses who partially contradict each other.  When are the witnesses believed? When are they reliable? When are they disqualified?  Is it possible that they will be partially believed?
But what if the Beit Din is insulted along the way?  Rav Nachman responds to this conversation with a clear statement: we do not worry about making the court seem like a laughingstock.  

After learning so many times about the importance of the image of the court, it is wonderful to read that the rabbis were, at least in this case, far more concerned about justice than about their image as righteous and infallible.