I am so sorry for their loss and the problems.  It may be hard for the one daughter to see things as fair in this matter but from what you have written it does indeed seem equal.  Now, she does not have to "sell" it to her if she does not wish to.  She can also "buy" it from her sister for the $9k.  Or the estate can sell it and the value split (which is the same).  She needs to understand that she is only entitled to half of the value, which is what she is having trouble with.  Good luck.