[Katsunami]

Personally, I do it like this:

- If I have all the books in a series as separate books:

The Fellowship of the Ring - Lord of the Rings [1]
The Two Towers - Lord of the Rings [2]
The Return of the King - Lord of the Rings [3]

- If I have a series as two or more omnibuses (for example, LotR book 1 and 2, and book 3 + Appendices)

Lord of the Rings, Volume One (no series)
Lord of the Rings, Volume Two (no series)

- If I have a series as one huge omnibus:

Lord of the Rings Complete (no series)

Then, if I read one of the books in the omnibus, I enter an EMPTY BOOK into Calibre; it's a book without any formats or files in it, but it's completely filled out as if it was a "real" book, including series, cover and everything. In the description I put something like: "See Omnibus: Lord of the Rings Volume One, Book 1".

It's also this empty book that will be marked as Read, after I've read it; the omnibus itself will never be marked as read.

I'm actually thinking of shifting the omnibuses to their very own separate library, or create a virtual library that excludes them. I must think about that.