1. A method performed in a system having a processor, a memory accessible thereto, and a user interface of unifying child nodes of a plurality of parent nodes from one or more other graphs into composite graph child nodes of a composite graph parent node in a composite graph, the graphs being stored in the memory and the method comprising the steps performed by the processor of: correlating the child nodes, including any of the composite graph child nodes, to produce one or more sets of possibly analogous nodes; displaying a representation of the set of possibly analogous nodes in the user interface and receiving an indication via the user interface whether nodes in the represented set are taken to be analogous; and making siblings of the composite graph child nodes of the composite graph parent node as required to provide a composite graph child node corresponding to each of the indicated sets of analogous nodes.