On-call person side key selection/

Hi all and thanks for any help in advance.

I’m looking to setup some type of blf-able system to show who is on call for the evening. The office has yealink 4x phones with multiple pages of blf enabled side keys. They would like to be able to press a button, before they leave that night, next to the person that is to be on-call for the evening and have their evening hours ring group go to that persons cell phone without conformation. What would you guys suggest to be the most logical way to handle this?

My though is to:
Inbound Route > Call flow control > Nighttime ring group > Only non DNDed extension(extension that only exist to act as cell forwards so as to not DND office phones).

I just cant find a good way to BLF DND extension.

Any help would be appreciated.