Determining fair value for property owned in a partnership can be approached in a business-like manner in order to avoid possible litigation, according to "Splitting up property is hard to do," from The Orange County (CA) Register. Unfortunately, this is not always what happens when it becomes necessary to place a value on jointly owned property.
If you are really interested in getting to a fair property value for all concerned, there's a formula for the situation where one party wants to purchase the other party's share and keep the property. In that case, each party chooses one appraiser, and each conducts his or her own appraisals. Then the two appraisers agree on a third appraiser to do another appraisal. The final value is an average of the two appraised values closest to each other.
Here's an example of how this works. Partner A's appraiser determines that the value is $650,000, and Partner B's appraiser values the property at $745,000. Then, the mutually-chosen appraiser conducts her appraisal and determines that the value is $690,000. The closest value to the third appraiser's estimate is by Partner A's appraiser: $650,000. The average of the two is $670,000. Party B's appraisal is thrown out.
This type of methodology makes both appraisers reasonable so that their value isn't the one that's knocked out.
A qualified estate planning attorney can help shepherd this process and refer you to appraisers as needed.
Reference: Orange County (CA) Register (November 7, 2015) "Splitting up property is hard to do"