You can upload the files and photos from the Yahoo group via the files and photos pages in groups.io groups. In photos, you also have to create individual folders manually, but once you have the folders, you can upload multiple photos through the upload dialog button. Files will upload an entire directory. If you have mixed files and photos in the Files directory, you'll need to set the new files page to allow photos in the files page. Admin, Settings, Files and put a checkmark in the box to allow photos in files.?
Been doing it for some groups I belong to that had no moderator or owner.?
You CANNOT download a usable membership list, however. You'll need to tell the members on the Yahoo group to join your new groups.io group.?
Bill in OKC