I see some utilities that crop an existing map, but what about doing the reverse?

Lets say I'm working on this great map of Ireland and then I decide I'd really like to include the rest of Great Britain? How do I make the map bigger without destroying the work I already have?

I've figured out a way to extend the map North (greater y coordinates) and East (greater x coordinates) but what about South and West? Negative numbers don't seem to work with the coordinates.

Any ideas?

Thanks for the help everyone....

But since no one else had any help/advice, I'll answer my own question for the benefit of others who might be having this issue.

I was able to do what I needed to with Civ4MapGenerator (http://forums.civfanatics.com/showthread.php?t=144414)and PlanetShifter (http://forums.civfanatics.com/showthread.php?t=137318). Civ4MapGenerator added additional tiles to the east and north of my map. Then I used planetshifter to move the map over and thus put the new tiles on the west and south of my map. Worked great. :goodjob:

If your map is saved right you can go into mydocuments/mygames/beyond the sword/saves/worldbuilder/mapname and open with Word Pad. Then look for this between player info stuff and the plot info stuff:
BeginMap
grid width=40
grid height=24
top latitude=90
bottom latitude=-90
wrap X=1
wrap Y=0
world size=WORLDSIZE_DUEL
climate=CLIMATE_TEMPERATE
sealevel=SEALEVEL_LOW
num plots written=960
num signs written=0
Randomize Resources=false
EndMap

and change the x and y spans.

Then down in the plots you can copy big chunks from one map to the other as long as you change the x and y designations. Edit/Replace in word pad can help, if used cleverly.

For instance, if your old map was Ireland and only went to x=30, but you had a map of Britain that was the same size, copy a chunk of text, spanning ten columns of plots, from the britain map into a new word pad file,
then replace all
x=
with
x=3. That will change all x=1 to x=31 etc...
Then copy that chunk into bottom of the ireland map. Repeat for the 40s etc...

Yea, which is very time consuming. Plus it doesn't help with adding tiles below the various axis'. The south border of the map is y=0, you can't add y=-1 to go lower. You can only expand in two directions that way. If you wanted to shift things you'd have to adjust the coordinates of every single tile.

The two programs I used did all of that with ease.