The Brains Trust have met again, as you used the magic words ‘manually write’, which always encourages us to think harder: we don’t like ‘manual’:-)

How about:
1 – create a H1 heading in your document
2 – Add an Element Report, H2, listing the Child packages and their descriptions
I’ve tried this, and in my version (eaDocX 2.2) it does work
3 – Add the main section describing the Parent package, children, use cases etc, also has a H2.

OR
When you print your package diagram which has the child packages, make it show the contents of the packages (which you probably already do) AND tell the diagram to print the Notes field of the Packages. Then you’ll have all the info you need, albeit on a diagram rather than on a table.