Hi, thanks for your reply.
I want to either:
A. Be able to edit the already set in / visible table of contents manually (add / remove certain headlines) – this way I could add the missing headlines to the visible TOC manually.
B. Link / include the missing headlines automatically in the generated / visible TOC. As I wrote before, 6 headlines are missing because the plugin does not see them (the two text sections with headers are divided by a custom section).