I am just wondering if there is any way to search within a group of features (or layer group from mxd) in the Geocoder widget? I have been able to set up searching within a single feature - Configure feature search—ArcGIS Online Help | ArcGIS , but wanted to be able to search for features within a layer group.
You can do that building a composite locator based on your different layers and create a geocoding service you can serve with your own ArcGIS for Server.
Then you can use this geocoding service in the geocode widget and "search" for feature in any layer you used ...
Hope this helps.