Thanks. It looks like Plex does have more user friendly features, but still no info about relations. That's a bummer.
It is really important to know the watch order (even if I had to specify it manually). When I think about it, Jellyfin probably fails even for the simplest watch orders like The Lord of the Rings; not to mention Stargate (Movie 1 -> Show -> Movie 2+3).
Thanks. I did miss that one. I was looking for a "Add to this collection" button inside a selected collection.
However I'm not sure if this collection is visible only to a user that created it, or an admin has to create it and it is visible to everyone?