Maven is built with the idea of one project-one artifact. What you would normally do in the situation you describe is create a separate POM in each of the modules with the top level POM specified as the parent. Each of the sub modules would then inherit the dependencies of te parent and be free to add additional module specific dependencies. In the top level Pom, you then use the declaration to declare the three sub modules.
One key advantage is that if there are dependencies between the sub modules (like you describe), then maven will automatically figure out the correct order to build them in based in those dependencies.