There is a new aggregation type for metrics called “Rollup”. This automatically sums metrics from children organizations that are based on the same organization templates.
To set up these automated rollup metrics, first create an organization to be used as a template. Any metrics that you want to be automatically calculated should have the update type of Rollup. Then create templated copies of that organization in a tree structure. Finally, update the metrics in the organizations at the bottom of the organization tree. The metrics in the organizations higher up the tree will automatically have calculated values based on the metrics in lower organizations.