For grid purpose we do some coding in the constructor of the TestSuite like the following
public GridSerenityProcessTestSuite() {
		super();
		
		String dirPath = System.getProperty("user.dir");
		getSystemConfiguration().setIfUndefined(
				ThucydidesSystemProperty.THUCYDIDES_DRIVER_CAPABILITIES.getPropertyName(), "browserName:firefox");
		getSystemConfiguration().setIfUndefined(ThucydidesSystemProperty.THUCYDIDES_STORE_HTML_SOURCE.getPropertyName(),
				"true");
	}
 just like we have to do for all the testsuite file. but may i know how to do something like two property files and make the testsuite a particular properties file.
Thanks in advance.