I think the update command is having too many duplicates from the child records. Presently, I have this:

UPDATE Client SET Status=InvoiceTemp3.AddDate
 FROM Client
 INNER JOIN 
(SELECT InvoiceTemp.NoClient,InvoiceTemp.AddDate FROM InvoiceTemp
 WHERE InvoiceTemp.RowNumber=2 AND InvoiceTemp.NoStatus=7 AND
  EXISTS (SELECT InvoiceTemp.Numero FROM InvoiceTemp AS InvoiceTemp2
   WHERE InvoiceTemp2.RowNumber=2 AND InvoiceTemp2.NoStatus=7 AND InvoiceTemp.NoClient=InvoiceTemp2.NoClient)) InvoiceTemp3
   ON Client.Numero=InvoiceTemp3.NoClient

Basically, if it would be just for the select, I would have:

SELECT InvoiceTemp.NoClient,InvoiceTemp.AddDate FROM InvoiceTemp
 WHERE InvoiceTemp.RowNumber=2 AND InvoiceTemp.NoStatus=7 AND
  EXISTS (SELECT InvoiceTemp.Numero FROM InvoiceTemp AS InvoiceTemp2
   WHERE InvoiceTemp2.RowNumber=2 AND InvoiceTemp2.NoStatus=7 AND InvoiceTemp.NoClient=InvoiceTemp2.NoClient)

So, if this gives 100 records, I need only the parent of those 100 detail records to be updated. So, I need to find the proper approach to include an UPDATE syntax from that SELECT command that will update the parent. Do you see how that can be adjusted?