splitting logfiles in weblogic 12c

We've an EAR containing several EJB jars and WAR files. Each has its own log4j config with rolling file appenders, pointing to distinct log files.
Weblogic-application.xml is configured to use our own log4j2 classes rather than Weblogic's built-in logging.

Despite all this all logging appears in the same log file (which is the log file for the EJB jar first loaded from the EAR).
It looks like WLS is using the same classloader for each of the archives.
Is there a way to force each (sub) application to use its own log4j configuration?