Should this be placed into a series?

[Nan]

I'm incredibly terrible at explaining things. However, I have always wondered if it is correct to list a book which has the complete books of the series into a series?

Example, https://www.goodreads.com/book/show/2... which is the complete series of this series, https://www.goodreads.com/series/7754...

[Renske]

An omnibus or a box set can be added to the series, as a non-primary work of the series.

[Nan]

Thanks!