When creating a new WebApp thru Portal/AGO, if you choose the WebApp Builder any related table data neatly appears at the bottom of the pop-up window when selecting a feature. Using one of the editing widgets, editing is very straight forward. However, if you choose one of template/configurable WebApps, related table data does not appear in the pop-up. The only way to make related table information appear is to toggle-on the associated relationship fields (within the parent feature class) when configuring the pop-up in the source WebMap. When doing this, the related table fields are jumbled/mixed in with the parent feature class fields within the pop-up in the WebApp. Furthermore, no editing of the related table information is allowed even if the editing capability is checked on in the WebMap. It doesn't make sense for it to be such a different, limited and unorganized appearance and process compared to the ease of use within the WebApp Builder. I've discussed this with an ESRI Support technician who has verified the issue. Apparently submitting this idea is the best course of action at the moment despite this being a huge limitation in my opinion that needs to be addressed.
