Extending Chimney Breast - Plastering Question

[Rob_Quads]

I have a small chimney breast in my new house - more a flue than chimney. It
is only 1 brick deep from the back wall, but unfortunately its not in the
middle. As i am putting an LCD on it i want to make it look central to the
room. I am planning to extend it to one side by around 250mm using stud
work/plasterboards/plaster.
The question is do you build it such that on the outfacing wall the stud
work is flush with the current plaster or (as i think you would) do you
build it such that its ~3mm back from the current plaster line such that
when its plastered its much easer to jet a seamless join?

A pic of what I am looking to do is at
http://www.convery.me.uk/temp/ChimneyBreast.jpg (Red = addition)

.... The best suggestion I have had so far is....

Make it flush, and fasten a sheet of PB over the whole face,
including thge existing breast - with a little thought you
can make shallow cupboards or shelves in the side. If you
just make an addition and skim the lot flat, you are very
likely to find a crack develops at the join.

To me this does sound like the most sensible. If I were to follow that attack is there a specific way to attach PB to a brick wall - the one i have seen most often on TV is using 'dolops' of plaster at regular intervals.

Is that the right way to do it?

 

[masona]

Can't see a problem there, use something like 5"x2" studding slightly sticking out on the edge of the fireplace wall to allow for the dot & dab adhesive thickness when putting plasterboard onto the brickwork so it's in line with the timber studwork. You could use 4"x2" on the rest of the studwork.

 

[legs-akimbo]

If the current breast is only small better still to have the boards flush with the existing plaster line, then tape the joint between old and new and skim over the lot in on go ....no messing trying to feather in that seamless joint