CLKComplicationDescriptor identifier for very old complications

I'm in the process of updating an app that uses complications that originally had a deployment target of watchOS 4.3. These complications used CLKComplicationSupportedFamilies defined in Info.plist. There are no CLKComplicationDescriptors in use.

Updated complications that use a new CLKComplicationDescriptor.identifier display correctly in the complication picker, but the original complication that's using CLKDefaultComplicationIdentifier displays "--" or "---" depending on placement. This happens whether you are using a ComplicationController instance or WidgetKit.

Using CLKDefaultComplicationIdentifier as the identifier when creating the CLKComplicationDescriptor doesn't work: the complication doesn't appear in the picker.

My question is there a way to "upgrade" an older complication configured by the customer to a new complication identifier? I'm not using WidgetKit for this project so a widgetMigrator isn't an option.

-ch