Overboarding with no coving

[Lifty]

Hi,
I'm overboarding a ceiling and removing the coving and don't want to replace it. What do I do at the edges where the ceiling meets the walls so that I avoid cracking?

The walls are hard-walled and skimmed.

Do I cut out the hardwall at the top and let the new board rest on that then make good with filler?
Or do I just butt to the wall, then scrim tape and skim over, plus caulk later?

Thanks.

 

[Monkey Boy]

The latter
no caulk
score deep with Stanley into wall at ceiling board level then skim

 

[ChrispyUK]

The latter
no caulk
score deep with Stanley into wall at ceiling board level then skim

No caulk

 

[Skullduggery]

Filler.