ElasticSearch: Facets from child documents

I have two documents in parent - child relationship and I want to get the number and also the max value of a date field from the children documents grouped by the value of the parent id. In other words, for every parent document I want to count its children and get its latest child (in a single query) and also get all the information from the parent.

I already tried more facets, but nothing seems to return the desired answer. Could anyone provide some insights about how to achieve this? Is it possible? Thank you in advance.