Ok, I managed to solve it myself
Basically I think I manually created the .localToGlobal thing (but i might be wrong on that).
1) I simply defined the ocean_mc original coordinates-
It wasn't a straight forward 0,0 because my movie was not properly centred, so I simply did a trace statement to find where the ocean_mc thinks it is.
2) Then I defined the original coordinates of a central zoom point for the island-
This was done by a non-sophisticated trial and error where I clicked to zoom in the island to set coordinates, and simply changed them little by little till i found the right place on stage, I am sure there is a beautiful smooth way to calculate those coordinates but I found the dirty trial and error way very quick
3) When an Island was clicked to be zoomed, I checked the placement of the ocean_mc clip in relation to it's original place and added that difference to the island's original centre points.
In code terms-
// So I started by setting original coordinates for the ocean_mc movie clip-
var origOceaonX:Number = -200;
var origOceaonY:Number = -310;
// Then setting the original coordinates for the zoomed in island
// (this is basically the coordinated that will place the island movie clip centre stage if it is clicked before anything is moved )-
var origIslandX:Number = 180;
var origIslandY:Number = 270;
// and then I defined 4 new vars-
// two to hold a new adjustments for the centre point for the islands-
// and two for setting the new centre point for the islands-
// and then when ever the zoom in button was clicked I looked where the ocean_mc movie clip was in relation to it's starting point and simply adjusted // the island's centre coordinates accordingly
// the open button function (called when the zoom-in button is clicked)
this.openIsland = function(theIsland:Object): Void
originIslandY = theIsland._y; <---this is for placing the island back to where it came from when you close it
originIslandX = theIsland._x;
centrePointAdjstX = Ocean_mc._x - origOceaonX; // <---- see how much the oceaon_mc clip moved from it's original spot
centrePointAdjstY = Ocean_mc._y - origOceaonY;
newCentrePointX = origIslandX + centrePointAdjstX // <--- add the change to the original centre point of the island to adjust
newCentrePointY = origIslandY + centrePointAdjstY
theIsland._x = newCentrePointX; // <--- the island centres itself 'to the stage' even though it's containing movie clip was moved about.
theIsland._y = newCentrePointY;
theIsland._xscale = 180;
theIsland._yscale = 180;