[ianbetteridge]

I don't think there's a way to do that in Context mode - so you need to switch into Planning mode, at which point "Add child" etc will work. Hit the "Switch" button if it's in your toolbar, or right-click on the task and select "Show in Planning mode".

However, consider converting the action into a project, particularly if it's the kind of thing you can work on in parallel to the rest of the existing project. If this is what you want to do, you just drag the action into the projects bar on the left, and it will convert it into a project for you.

So, for example, if your actions for "Start a circus" include "Hire a big top", "Buy an elephant", and "Buy a top hat", group each of these in one "Starting a Circus" folder - if they're not linear actions, this is often easier than having indented steps within a single project.

Hope that helps!