Devote Chaos Sorcerer to Undivided?

Hello, i just got Kholek Suneater and wanted to give him a Chaos Sorcerer, and just realized there is no (obvious) option to "devote to Undivided" on the Paths of glory mechanic.

Is there a way to devote do Undivided or no? If not, is there any mods for that, i think it would be cool for a undivided army.

Thank you in advance.