Overwrite AGOL one layer within a multi-layer web service

Why are you trying to overwrite a single layer within the feature service? Are there schema changes to that layer?

If there are no schema changes, you can target that sublayer and truncate it (using FeatureWriter), then insert the new data (other sublayers remain untouched as long as you don't connect the layers you do not want to change to the FeatureWriter).

If there are schema changes, it’s more involved. You can use HTTPCaller to call the ArcGIS REST addToDefinition / deleteFromDefinition / updateDefinition operations to add/remove fields or modify aliases/domains. Changing field data types on an existing layer isn’t supported (https://support.esri.com/en-us/knowledge-base/faq-is-it-possible-to-change-the-field-data-type-create-000031634), I am not too sure about changing geometry of an existing layer (I’ve never tried).

More Information on ArcGIS REST endpoints:

• Add To Definition:https://developers.arcgis.com/rest/services-reference/online/add-to-definition-feature-layer/
• Delete From Definition: https://developers.arcgis.com/rest/services-reference/online/delete-from-definition-feature-layer/
• Update Definition: https://developers.arcgis.com/rest/services-reference/online/update-definition-feature-layer/

Thank you for your response!  Yes I am only trying to truncate and insert as you've described; there is no schema change.  In my case, it’s merely convenient to publish the three layers from ArcPro as they are related and so if published together as a Web Layer from Pro, in AGOL they remained grouped together in a single feature service.  Only one of my three sub layers will change with any regularity, so that’s why I’m trying to create a job targeting only one of them.  

I’ve often used FME to update single feature services that contain only one layer, but have never attempted to update one or more sublayers in a service that contains multiple layers.  So my disconnect is with understanding how to handle sub layers in FME.  When I select the parameters button within FeatureWriter, it allows me to select a feature service, but not individual sub layers within a feature service.  In my example, the feature service name is Road Rock and there are three sub layers beneath that named Road Rock, Road Rock Yearly, and Road Number (it’s confusing because one of my sub layer names shares the same name of the feature service). 

To keep the discussion cleaner, perhaps it would be easier to refer to the sub layer “Road Number” as the one I would like to update.  So then if I wanted only to update “Road Number”, where do I indicate that in the parameters?  

In your screen shot, I can see Layer1 and Layer2 in the Feature Types window, and you’ve selected Layer2 in the Layer Name field.  However, for me that’s where my feature service name populates “Road Rock”, not the sub layer name “Road Number”.  I don’t see “Road Number” in any sort of drop down menu to populate the Layer Name parameter value.  I could type it in there I suppose, is that what you did?

Just for reference, here’s a screen shot below of where the option to publish a feature service with multiple sublayers exists within ArcPro; see note where it states all data layers in the map will be published.  Conversely, to publish a single layer, you’d just choose Sharing from the right-click context menu of the layer in the TOC.

Fantastic, thanks for your detailed reply; much appreciated!  Following your instructions I was able to find and select the sub layer I needed.  Sometimes GIS folks like me just need a visual.  😁

This duplicates what you’ve already shared, but here’s my screen shot with steps I followed after first selecting the feature service.  I’m currently using 2024.2 so not sure if these menus are the same in current version given 2025.X introduced a number of interface changes.