DVD Volumes with multiple episodes

There is a series, "A History Of Britain", which is listed in theTVDb by individual episodes.
The NTSC version came in a 5 volume DVD set with 3 episodes per volume.
Having read the metadata info it seems there is not a mechanism to handle this situation.
I suppose one could add something to theTVDb but it would be a duplicate which they don't like.
Is there a way to reflect this in Serviio because at present the volumes are categorised as Genre Unknown.
I don't quite know how to fix that.
The NTSC version came in a 5 volume DVD set with 3 episodes per volume.
Having read the metadata info it seems there is not a mechanism to handle this situation.
I suppose one could add something to theTVDb but it would be a duplicate which they don't like.
Is there a way to reflect this in Serviio because at present the volumes are categorised as Genre Unknown.
I don't quite know how to fix that.