iv'e never had a problem obtaining a duplicate history books from franchises, most traders in this industry will or should have a good enough relationship with the franchise to make it easy enough to obtain,though these days duplicate service invoices are a problem due to data protection /customers address on etc.
the bmw parts lads as mentioned can make things awkward for good reason - if they issued these items without any questions or cheaply the result is the dodgy side of this trade would just take the piss / advantage and get creative, there will come a time when its all database only like the mot test, once its all online this will rid the trade of more scumbags like the mot online data check did regarding bent mots, and that is a good thing for the rest of us.
the ebayer's who make a living selling service books don't have many morals, there will be no doubt an element of purchasers who get creative with their purchase, the ebay sellers know this, sadly the people doing this practise are wise enough to work out when a franchise closed or was sold etc giving them a good idea how to create a false history.
i have even had in the past a muppet turn up some years ago with a bmw with a book from another car, they hadn't changed it just presumed a different book was ok