Then you could manually operate on the knowledge base, something like this:
KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();
// add you process definitions here...
kbuilder.add(ResourceFactory.newFileResource(subfile), ResourceType.BPMN2);
kbase.addKnowledgePackages(kbuilder.getKnowledgePackages());
// if you like to remove it you can remove the package
kbase.removeKnowledgePackage(packageName);
So you can load the process definitions from whatever source you want, if not already supported by ResourceFactory you can implement your own...
Please nore that building knowledge base is considered a heavy operation and should be rather reused instead of rebuilt frequently.
HTH