When you have an odd number of shares in a joint brokerage account they cannot be split equally. The normal practice is to let one party choose if they want the over or the under on the first item, and then the other party choose on the next item.
We track the current values and perform a True Up accounting as of a date certain, usually close of business on the day of the mediation dividing up the shares so we eliminate the risk of stock movements up and down.