Ordering certain topics by Date in navigation pane?

[Merion]

Here's the thing:
I have a topic named timeline - it's a time period topic and basically is a list of time spans that give a rough overview of the history of my world. Like 1000 years golden age of dwarven kingdom, then 200 years of anarchy, rise of the human empire, etc, etc.
Now I also have topics for some of these timespans as well as singular events (e.g. assassination of the dwarf king) that are more fleshed out.

I would love for these topics to be contained by the timeline topic and be in the correct order in the navigation pane.
Of course I could use prefixes (order by prefix is my standard for the whole realm), but that would mean that I have to edit all later topics when I add a new incident or timespan.

Anyone has an ideas how to achieve this?