Here is a map of all of the feeder marches planned to join the anti-war rally around 1st Avenue/49th Street this Saturday, Feb. 15.
The city has not approved any marches, only the stationary rally.
The same web site provides legal info regarding your rights as a demonstrator in NYC.
After my experience with the Matthew Shepard march in 1998, I don't trust the police to follow the law. Their approach has often been to break it anyway and let people sue.