if this is happening you probably have an organization problem. Your best bet is to, rather than split a script into multiple files, to split it into multiple plugins.
Another recommendation I can give is to keep things organized by prefixing everything in each file with a unique tag, like:
#include <gaben>
would prefix every function with GB_ or something.
Pawn doesn't require any specific ordering because logically it doesn't make sense for a scripting language to have that.