The packs do work with DCS, all do.
Re your comment on using one set from one pack to another, that would be very very hard to accommodate, due to clothing shapes, and so fourth, so.. when you see a pack containing multi clothing such as the Knight armour pack, Viking Clothing pack, those packs are made specifically for that purpose of totally modularity
When a costume pack is sold on its own(other than when its a single release from the larger pack), it will always be for its own use.
Steve