Beyond Reality discussion

Thought I'd toss this out for anyone who might be interested.

Humble Bundle is currently offering a ebook bundle of all of R.A. Salvatore Forgotten Realms Cleric Quintet and Drizzt books. I picked up all 32 of them for $15.

Which leads me to a question. I know I can be a bit odd on the subject, but I have a thing about ebook tags being accurate and so had to go in and get the series names and numbering all correct. (Tags are amazingly clean on these, barely had to touch anything.)

The part that is frustrating me is that Servant of the Shard is both book 3 of the Paths of Darkness Series (a 4 book series).
Its also book 1 of the Sellswords series.

The epub format does not allow for multiple series names or multiple numbering. I've got to choose just one.

So which series would you assign it to?

Oh and there's 11 days left on the bundle.