The children creator is a special operator that prepares the parent population for reproduction as used e.g. in the GeneticAlgorithm. After the selection operators have been applied the scope tree is divided into a Remaining and a Selected population. That is, the whole population is transitioning into the new generation. The remaining scope contains the old population and the selected scope contains all parents that have been selected for reproduction. After the selection steps these parents are stored simply as a list of sub-scopes. The ChildrenCreator then transforms this population such that it creates new children and puts batches of ParentsPerChild number of parents as sub-scope to each new child. Afterwards the crossover operator can be applied to each child and is responsible to combine the variables in the parent scopes and put these into the child scope.
The following image should visualize this process graphically.