Recently I've been studying dCOEA (https://ieeexplore.ieee.org/abstract/document/4553723/) and trying to implement it for a project. However I got stuck in the EA process. While the parent individuals of each subpopulation have already been evaluated in the cooperative/competitive process and their respective Pareto rank and niche count calculated, after the crossover and mutation operations on each subpopulation, how are the child individuals evaluated? Since an individual needs to be combined with representatives from other subpopulations to form a valid solution that can be evaluated. I've been thinking on simply combining the child individuals with those representatives to evaluate them. However, I don't know if that is the correct form to perform this process.

Also, since there is a possibility that the individual defined as the current subpopulation's representative might not be selected from the mating individual pool for the next generation, how is the new representative defined? I've been thinking on using a random selection but that will definitely affect the quality of the solutions obtained and I know that answering the first question might answer this one as well.