Merging maps frm GMDL

[fifo_thekid]

Hi everybody
I have 4 folders each one has a map of a city
I want to merge them in one folder so that I can make one file for the iPhone xGPS
How can I do that?

[thamdx1]

I have downloaded a city map by separated 2 part, i need to merge them to together so it become one.
I also wondering how to do that.. . any tutorial to help?