How to smooth old flakey emulsion?

[RP66]

I am about to emulsion our kitchen but have a few areas where the old emulsion has gone flakey.
Tried to sand it smooth but it seems impossible as the old coat just keeps peeling back and what was a small area is now twice as large and has a hard edge.
Is there an easy way to overcome this to get it all smooth.

Attach photo of cracked emulsion.

Thanks.

 

[Chivas69]

It looks like Matt over silk. I think you're going to have to scrape as much off as possible and sand again