Just some experimentation with Esri-Leaflet. Basically, we have a feature service for our parcel data that is split into two layers: geometry and attribute data. The attribute data is a related table. Natively, Esri-Leaflet doesn’t query data from a related table. Luckily Esri-Leaflet-Related exists. It’s in beta and uses a release candidate build (I think that’s the term) of Esri-Leaflet 1.0.0, but I was able to use it to pull data from the related attribute table and make it so that when the user hovers over a parcel (geometry), an info pane shows the parcel’s address (related attribute table). When the user clicks, a table appears with more info about the parcel (related attribute table).