You should do this report from the LineItems table, with sub-summaries by QuoteID and by Quotes::SalesEngineerID (and no body part).
Alternatively, add a calculation field to the Quotes table = Sum ( LineItems::Value ) and a summary field totalling this field.
The summary value you get over a relationship will ALWAYS be the total of the related set, no matter where you place it.
I used your Alternative method as there were a whole host of other things on the layout that I hadn't mentioned to avoid confusion.
It now works like a charm and I can use the Quote Value field (Quote Book) on another couple of layouts and reports.