The
http://www.gmayor.com/ManyToOne.htm add-in, briefly referred to in Paul's reply, is explained on the web page and comes with an example file and worksheet (while Doug's add-in includes all the mentioned supplementary functions, I provide similar functions, should you require them, as separate compatible add-ins.
The things to remember when using the Many to One add-in it is that only the fields that are repeated in the table should be designated as 'child fields', and a new document begins whenever the common key field changes, so the data should be sorted on that field.