There may exist multiple, symmetry-equivalent (from the graph perspective) bijections θ -1 • φ from the subset of atoms of the replacement fragment to a subset of the atoms on the substructure of the parent matching the query fragment. In this case, we solve the orthogonal Procrustes problem for all of them and select the bijection for the installation procedure that gives the lowest alignment error in eqn. . As opposed to choosing one of the graph-symmetry-equivalent bijections at random, this procedure to select the bijection with the optimal alignment can be important. E.g., when replacing a two-fold disordered pyridine rotamer with a corrected pyridine ligand, there are a total of twelve bijections between the pyridine replacement and the two-fold disordered pyridine query, four of which describe spatially correct [flat] rings and eight of which describe spatially incorrect [taco-shaped] rings.