You all nailed it! I went ahead and used union and used the resulting multipoint to query the polygons. I suppose I could have just created a multipoint from my points as suggested by Robert but was well into my union code before reading his response.
If you are interested, here is the code:
require(["dojo/_base/array","esri/tasks/query","esri/geometry/geometryEngine", "esri/SpatialReference"],
function (array, Query, GeometryEngine, SpatialReference) {
var urlParcelMap = dataLink + "/Assessor/PropertyMap/MapServer/";
var arrayOutFields = ["PNUMBER"];
initQueryTask(urlParcelMap, 4, arrayOutFields);
query.where = "PNUMBER IN (" + searchString + ")";
var pnums = queryTask.execute(query);
pnums.then(function (fset) {
var pts = array.map(fset.features, function (feature) {
return feature.geometry;
});
var union = esriConfig.defaults.geometryService.union(pts);
union.then(function (results) {
arrayOutFields = ["PARCELID"];
initQueryTask(urlParcelMap, 5, arrayOutFields);
query.spatialRelationship = Query.SPATIAL_REL_INTERSECTS;
query.geometry = results;
queryTask.execute(query, showCompQueryResults);
});
});
});