We are gearing up to collect data using our iPads and the same workflow as last year. Field workers have updated some of the locations and I will calculated those locations in my Arc Map project which will be republished as the Service. I would like to know what is the best way to update the existing maps on AGOL to reflect these new locations and still maintain the existing attachments (photos) and other information. I downloaded a FGDB for each project and will update the lat/long fields. Do I republish the feature service and I'm good to go? What about the Append in Update Data on the on the Overview page for the existing data on AGOL? Is this a better way to go? There are several supported file types. Which is best to use if any?
If you are just updating the lat and long values after making edits in collector, for your service you can use the field calculator in ArcGIS Online - Calculate field values—ArcGIS Online Help | Documentation
You can append data directly in ArcGIS pro or make edits in ArcGIS Online. it's a bit redundant to download the file geodatabase, as you can access these services in your desktop application to make changes.