I asked you the version detials because the services in WmRoot package (which is used internally) varies/changes from version to version (as per my knowledge).
According to me there should be one service that might tell the whether the startup/shutdown services are loaded/unloaded within a package.
If we do not find the a specific service in WmRoot I am quite sure there must be a Java API publicly or privately available.
We need to explore more on the above points.
#webMethods-General#Integration-Server-and-ESB#webMethods