gistfile1.json

{
  "query": {
    "bool" : {
      "must" : [
        {"term" : { "a_parent_field" : "a_value" } },
        {
          "has_child": {
            "query": {
              "custom_sore": {
                "query" : { "match_all":{} },
                "script" : "doc['a_child_field'].value"
              }
            }
          }
        },
        "script": "_score[0] / _score[1] * some_constant"
      ]
    }
  }
}

The script on the must clause in the bool query is what I'm not sure how to achieve. I know that's not legal syntax, but it should convey what I'd like to do. How do we go about doing something like this?