pcmerge() - Any way to find the indexes that were merged

MATLAB 2015b has a function pcmerge(). It takes pointclouds A and B and tries to merge them based on the proximity. It returns the merged pointcloud. I am interested in knowing which indices from A and B were matched and merged together. I cant find any info on this.. Is there a way to find these indices rather than manually searching it based on the merged pointcloud? It will take extremely long for such an approach if the pointclouds are too big.