As mentioned on Mastodon (https://mastodon.social/@dpom@fosstodon.org/113460954769241417) there seems to be no way to do it at the moment :(

That worked! Thank you! The trick is really to embed the bookmarks into each other :)

Thanks for the reply. When I disable the toolbar, the bookmarks are correctly placed in a folder but the folder is not visible in the toolbar anymore. So I can either have the bookmarks separately in the toolbar, or in a folder but not in the toolbar. The combination of both seems to be only possible if I move the bookmarks by hand in the UI :/

Thanks for the response. I’ll have a look at it. It still astonishes me that there is no off-the-shelf solution to such a trivial and common use case.