Originally Posted by BobK99
I wonder why KDP insist on it then :
Amazon Kindle Publishing Guidelines, 3.3.7
I guess I'm misinterpreting; it does after all say 'the file'; so I suppose they mean 'At the beginning of the first volume, put a link to future volumes. Future volumes should be added to the existing EPUB file.' If so, I don't think they support my idea - publishing a part-work in stages, unless I just have links to 'volume N - tbs'.
I'm pretty sure this refers to 'Omnibus' editions, ie the collected stories of Sherlock Holmes or Lord of the Rings I-III. In those cases a comprehensive TOC spanning all volumes makes a lot of sense
With the way every reader stores its files differently, a scheme for linking between epubs would be very fragile, and none exist AFAIK. Neither do I believe it would be a good idea, as any one person might not even own all volumes.