book of rust relics allowance

Ok this might have been asked before but could not find it...
I know that in order to take a relic from the book of rust you need a CoS warlord. Does this work if you give a warlord trait with tolerated ambition or do you have to have your armies warlord as CoS?

For example i have a triple patrol with two kabal and one CoS detachment. I make Drazhar my warlord, who isnt CoS, can i then give tolerated ambition to one of my Succubus in the CoS detachment and unlock the relics from te Book of rust supplement this way or do i need to make the Succubus my armies warlord and thus rob Drazhar of his sweet sweet rerolls??

No, with Tolerated Ambition you only give a Succubus a warlord trait, but she doesn't actually become the warlord. Unfortunately Drazhar as a warlord means no relics from the Book of Rust.

damn... i had a feeling this would be the case but didnt want to believe it... thx