Hmm. I thought you couldn't update a table using an aggregate query (ie. distinct keyword or group by). You have already gone way above and beyond the call of duty. I just appreciate the time you have given like I have said before.

Just for fun, here is an example of the way we used to do it in Access. It just shows the process for one group.

UPDATE [Vehicle Detail] SET [Vehicle Detail].ReturnDate = #4/29/2013#, [Vehicle Detail].ReturnSource = 'ReturnProcess'

WHERE ((([Vehicle Detail].SerialNumber) In (SELECT TOP 15 [SerialNumber] FROM [Vehicle Detail] WHERE ((([Vehicle Detail].ProgYear)='12') AND (([Vehicle Detail].LeaseCycle)='1') And (([Vehicle Detail].ModelName)='Focus') AND (([Vehicle Detail].RiskNonRiskFlag)='R' AND (([Vehicle Detail].region)='SouthEast') And ReturnDate Is Null))

ORDER BY [Vehicle Detail].DeliveryDate,[Vehicle Detail].SerialNumber)));