Currently, there is not a built-in method to merge lists.
Here is a suggested method to ensure the structure and all bookmarks are moved accurately:
- Create a brand new list or decide which list is best to use as the base list to which you will add the other bookmarks to.
- Export the other lists as RIS files using the Export Citations menu.
- Import the RIS files as bookmarks only (Note: you could combine the RIS files using text edit and import as one list but this would have no structure. Building the structure around the items would take longer than manually adding bookmarks - this not suggested but is an alternative way).
- If possible have two screens side-by-side, or if you only have access to a single large screen, use two separate browser windows open side-by-side. This helps speed up the process of replicating the list structure and notes from one list onto another.
- With all the bookmarks now available, open the list you have created or want to add to in one window, and the first of the old lists in the other window.
- Create and replicate the structure of the existing list.
- Search and add the bookmarks as you go, following the list structure creation.
- Work your way through the lists until you have one new list or edited list.
- Archive or Delete the older lists.
You may also wish to refer to How to export a reading list as a RIS file and How to import a reading list as a RIS file.