Troublesome paint

Hi, the best solution would be to remove all loose and flaking paint first, then apply a suitable stabilising solution/sealer to the wall. After the surface is properly prepared, it can be filled, sanded and repainted with a suitable paint. The wall should be checked first to make sure there isn't an underlying damp or moisture problem.

Remove all flaking paint and then treat with zinsser guards/ peel stop. Those products bind substrate and glue down peeling edges. Apply fine filler over the affected area and sand back once cured with 120/180 grit sandpaper so you can see the repair. Spot prime the area with sealer to prevent flashing and paint over with your chosen topcoat.