Yes, UIMA-AS will do the merging for you if you run the annotators in a parallel step with a custom flow controller. For an example see: examples/descriptors/flow_controller/MeetingDetectorTAE_AdvancedFixedFlow.xml Assuming the annotators are independent of one another, the resultant CAS would be equivalent to running them in sequence. Throughput will also be improved if you use a multi-core machine or deploy some or all of the annotators remotely.
A CasMultiplier could be used if you already have produced the output XMI CASes, but would require user code to check that the sofa data is the same and to copy the annotations into the new output CAS. ~Burn
