Hallo @ All… 
I sorted my open tabs in groups on one of my Windows PC in the Brave Browser. Then I saved all tabs (groups) as bookmarks. Then I used the bookmark manager to export these bookmarks to an HTML-file to import them again on another Windows PC using the bookmark manager. Unfortunately, this does not work as it is wanted. Only all tabs, but not the groups (where the tabs were sorted) are restored.
How do I get it that the groups (including the associated tabs) can be manufactured again on the target PC as on the start PC …? 
Thank you in advance… 
@Garde-InfoMedia you can use Brave Sync to do this, adding both devices to the Sync chain and ensuring that the Saved tab groups
and Open Tabs
data types are toggled “on”.
Thanks for the answer. Everything is already set up exactly as they described it. Even after removal and re-setup of the sync chain unfortunately nothing happens… 
But by the way:
Why are the html backed up/exported open tabs sorted into groups not imported again as they were exported. To create 113 open tabs again in groups, I actually want to avoid and that should not be the point of the matter…