A question I have seen a lot over at the Commons, but been too lazy to make a tutorial for till the @ mention from Debbie, is “Why is my subcategories not displaying in my menu?”
Read more for very quick, very easy step-by-step screenshot tutorial.
And viola! It works.
Remember, if you add a new subcategory, you need to go back and edit the custom menu manually – it only updates “parent” (i.e. top level) pages automatically when the tick-marks shown above are clicked.