Is it possible to add or delete related records when editing a related table in ArcGIS Online Map Viewer?

Answer

Yes. Map Viewer in ArcGIS Online supports adding, editing, and deleting related records.

If you created a relationship class in the geodatabase in ArcGIS Pro before publishing a hosted feature layer, and if the hosted feature layer was created using a template that includes a relationship class, or the hosted feature layer was created for a form containing a repeated section in ArcGIS Survey123 Connect, you can add related records to the form. 

When you create a form in Map Viewer, you specify what elements the form contains and how they appear. Now, we have added a new form element for related records. When you’re creating a form for a layer that has one or more related tables*, you will now see a new form element for related records under ‘Form elements’. To add the element to the form, you can either drag and drop or simply click ‘Add all’. With this simple action, editors will now be able to edit features in the layer and the records in the related table.

Map Viewer supports editing related records that meet the following criteria:

• An editable ArcGIS Online hosted feature service with at least one related table
• Feature-to-Table or Feature-to-Feature relationship
• Relationships with a 1-to-1 or 1-to-many cardinality

Other things to note:

• Although the related record is contained within the table, the related record form element must be added on the parent feature’s form.
• To add a related record to a feature, the feature must be created first. You cannot add a record while still actively editing the parent feature.
• Applying restricted permissions to the hosted feature service (such as add only or delete only) will also apply to the related records.
• The related features and/or tables must all be added to your map to work as expected.