Okay, so I have set up a 3 level deep relates between a poles feature class, a signs table, and an attachment from the signs table. I have the relationship using GlobalID>PoleID(GUID) from Poles to Signs table, but then I also have created an attachments relationship from the Signs table to the Signs__ATTACH table. I noticed when publishing the feature service of my map to our ArcGIS Server, there are two services (Feature & Map), yet the Signs__ATTACHID only shows up under the Map service and not the Feature service. Next, I added item for the feature service to our AGOL site in order to create the webmap for field collection using Collector. The WebMap is all set up and shows only the Poles features and Signs table. When I went out into the field to collect poles and associated signs, even though the attachment paper clip icon showed up on my signs table window, I took a picture, but was unable to save it to the associated sign. My question is, what am I doing wrong, and could it possibly be that attachments cannot be related to a table within Collector? Of course, Esri provides no documentation on any of these types of issues, so I have to turn here for answers. Please help if able.
If you enable attachments to the signs table then the photos are automatically attached to the sign record in the sign table. You do not have to create an additional relationship. The only issue with storing photos in the table is that in a web map, you can only view them by first clicking on the point (pole) then viewing a related record, then viewing the photo. I have a similar set up for sign poles and multiple sign panels in a related table. But I chose to enable the photos on the poles so I could view all photos quickly instead of viewing a related record and then a photo. Not sure if my answer helps.