Multiple Flatten Polys

I may be the only person who doesn't know this - but I pass it on just in case:It seems that the default FL******.bgl files in FS9 can overlap and have flatten polygons repeated in two adjacent .bgl files. I discovered this when I was moving another default FS airport. It so happened that not only was the default MS airport about 500m west of where it should be, but there was also a stream missing. I duly used LWMViewer (thanks again Jim Kier) to remove the flatten poly, AFCAD to put the runways in the right place and Ground2K4 to correct the stream and several roads. When I was done I was puzzled to note that the original flatten was still there! This was obvious from the stream which now "climbed over" the old flatten. After some checking I found that the flatten needed removing from two adjacent .BGL files, (the airport was right on the edge)Geoff