You can import your existing bookmarks into groups inside tabExtend. This gives you the ability to visually rearrange and organize your bookmarks in a new way. To open the import modal go to the settings menu in the right-hand corner of the overview and select Add bookmarks or top sites.
Inside the modal, you can choose what bookmark folders you want to add as groups. You can also add a group containing your 10 most visited sites. Both options need a one-time permission before the groups can be created.