How can I get a single event handler/automation chain to fire correctly when multiple documents are created concurrently using a structured template?

Background:

My application has several documents which are created inside a folderish document via a hierarchical structure template. The container document is created and the child documents are automatically created at the same time using a structure template.

I have an automation chain which, when fired, reads a child document type and initializes the child document's metadata based on the document type it read.

I want to have a single event handler which will fire the automation chain mentioned above when each of the child documents are created. The differentiation between the documents is handled in the automation chain so the event handler should enable all the child document types that will be created in the container document.

I tried selecting all of the child document types in a single event handler pointing to the automation chain. When this event handler/automation chain is fired; document not found errors are generated.

This event handler/ automation chain works if I only enable a single document in the event handler, but obviously the other documents in the container are not initialized.

The only way I can get the scenario above to work for multiple documents is to create individual event handlers for each document type. Each individual event handler is fired on document creation, but calls the same automation chain.

As the project moves forward there will be many different child documents created in the container folder. I'd like to have a single event handler/automation chain pair handle the child document initialization. I don't want to create a separate event handler for each child document type.