Advanced Map can easily rename locations. Just go to the very last page (the one to the right of the wild POKeMON), select your desired town/route name (or use your current selection if you'd like), rename it using the field to the right of the dropdown box, and then hit change name. Hit it again and it should finally go through. If you are talking about adding more spaces for custom map objects, advanced map can do that too. Hit the puzzle piece on your desired map, click one of the menus, find change block amount and enter how many blocks you need added (E.G. 10), and then go to those to add in your custom objects. About town/route names, I have no idea how to add in new town/route names without touching the existing ones. If I change names, I just use the unused ones such as sevii isle 22, and if I need more, I just use the names that the Island 7 chambers use (Milford Chamber, etc), and then make it so that chambers name doesn't display when you enter it. That's for FireRed. For Emerald (but not Ruby and Sapphire), I will use the FireRed towns as for some reason those are in the game, and all of those go unused (except for Navel Rock and Birth Island), making them perfect for anything new I might add in.