Ground2K streets and coastline over custom ground textures?

HiI have the following 2 problems:I have an Area of 2x4 custom ground texture (the usual 022020220202...bmp thingy)Problem 1) That obviously excludes the street that original lies under that and removes all the autogen. No problem as the street was palce wrong anyway so I wanted to redo that street in Ground2K (VTP....). Unfortunately the newly designed street will be excluded as well where it overlaps with the area of my custom ground textures.Problem 1) my custom ground textures extend in the water, so I want to remove them where they don't belong (in the water) and redo the coastline. I guess this alos can be done via Ground2KI'm a complete newbie to Ground2K , Is there a step by step instruction somewhere that could help me or does anybody of you knwo some great tricks that might help me??Thanks a million in advance!Mario