@Override
			public void modifyLatest(MergeProgram mergeProgram) throws Exception {
				Library library =
					mergeProgram.createExternalLibrary(libname, SourceType.USER_DEFINED);
				Namespace namespace =
					mergeProgram.createNamespace(library, parentNamespace, SourceType.USER_DEFINED);
				ExternalLocation externalLocation = mergeProgram.addExternalFunction(namespace,
					label, address, SourceType.USER_DEFINED);

				Function function = externalLocation.getFunction();
				assertNotNull(function);

				Program program = mergeProgram.getProgram();
				Parameter parameter1 = new ParameterImpl(param1, new DWordDataType(), 4, program);
				parameter1.setComment(comment1);

				mergeProgram.updateFunction(function, true, new ByteDataType(), parameter1);
			}
The external function merger only detects and merges source differences when a name
difference is being merged.
Ghidra/Features/Base/src/test.slow/java/ghidra/app/merge/listing/ExternalMergerAddTest.java