I have three first-level pages, no child pages, linked to in my navigation, e.g.
About | Topic 1 | Topic 2
and then a fourth (and possibly fifth, sixth…) page
Topic 3 that has three child pages (
Sub-topic 3.3), so the menu then should receive two levels, realised by a drop-down menu for
About | Topic 1 | Topic 2 | Topic 3 | Sub-topic 3.1 | Sub-topic 3.2 | Sub-topic 3.3
Normally, the links to children, when created through the WordPress menu backend option, would look like
, but should be turned into
domain.url/topic3/#sub-topic-3.1, for child pages only.