Function_score with nested geo_location

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I'm looking to do something very similar (but with a date, rather than a location). The original poster laid out a very good example mapping and document set, so I'll ask my questions based on that.

My goal is to return a set of documents based on a query that references properties at the document root, then apply a decay-based function score to the resulting set, but using a nested object property.

If I remove the nesting from the equation by adding a nonnested_geo_location property to the document root, exactly like locations.geo_location, in terms of mapping and values, the function score documentation page provides enough examples to make the approach clear:

GET my_index/_search
{
  "query": {
    "function_score": {
      "query": {
        "match": {
          "name": "doe"
        }
      },
      "functions": [
        {
          "gauss": {
            "nonnested_geo_location": {
              "origin": { "lat": 42, "lon": -88 },
              "scale": "100km"
            }
          }
        }
      ]
    }
  }
}

By way of examples provided in an answer to a different question, I was able to figure out how to apply the decay function scoring based on a nested object property, but without a query first running to potentially narrow the set of documents to which the scoring is applied:

GET /my_index/_search
{
  "_source": ["name", "locations"],
  "query": {
    "nested": {
      "path": "locations",
      "query": {
        "function_score":{
          "functions": [
            {
              "gauss": {
                "locations.geo_location": {
                  "origin": { "lat": 42, "lon": -88 },
                  "scale": "100km"
                }
              }
            }
          ]
        }
      }
    }
  }
}

I've been unable to find any examples that marry these 2 needs. How do I formulate a query that references properties from the parent object in order to narrow the set of documents to which a decay function score that references a nested object property is then applied?