Designing a list

Hey all,
I have yet to play my pointy eared sociopaths in 8th Ed but I am helping a friend design a force. They picked up an used lots and we were pouring over the codex trying to see what we could build. How do Incubi, Mandrakes, and Scourges work with the new obsessions? They have neither Kabalites, Cult, or Coven. Does that mean whatever detachment they join would have to be general Drukhari and this not get access to an obsession? Let me know thanks.

Yep basically. You can add them to any detachment without losing the obsession for other units but they don't benefit from them

So kinda like Cypher and the Fallen in CSM (a book I own, my friend owns the Drukhari one). Thank you.