Hopefully I am just being a bit thick, but I cannot seem to find a way around the following problems with demolition in different phases:

Removing External Insulation from Existing:
My existing building has render and insulation on the outside face of the structure, where my new build joins I would like to remove these outside layers back to brick, then rendering and skimming ready for internal decoration. This would also give me back 85mm of room space, stolen by restrictive planning rules!! Anyways I cannot figure out how to do this "localised" demolition. . . .

Roof Demo:
Similarily, I need to cut a chunk out of my existing roof where my new one hits it (not a pretty site - also thanks to the planners) But if I do this in my Phase4, then my Phase2 has an irregular hole where the roof should be. I have done a workaround by slipping in a patch but the join lines show up!! Any ideas??