I hope it is not already mentioned somewhere else.
I'd like to some approvement if I interpret the rules correctly.
Let's say I have a Kabal, A Cult and a Coven Detachment each pure with respective obsessions.
I think it is fine to put a 5 man(girl) whych squad and a 5 man Kabalite squad in a Coven Raider and deploy them up together, or with screaming jets.
That is totally fine right? I haven't found something that says otherwise.
Your life shall end as it began; bathed in blood!