How do I add the correct Edit Layout to the Action Menu for a Custom Child object in Redwood?

Summary:

The Edit Action for Custom Child objects doesn't display the correct page layout.

How do I correct this?

Per the documentation for 24D, I need to move the code to the child object layout in the BeforeInvokeSmartAction event.

The custom child objects do not have any Events, Event Listeners or Action Chains listed under them.
Do I need to create these from scratch, and if so, is there any documentation on how to go about this?

Version (include the version you are using, if applicable):

24D