Multiple Tabs alternative
You can open multiple tabs in your browser, and upload each folder into the respective sets at the same time.
1. Click on + Add Set to create and name your sets according to how your folders are organized.
2. Open Multiple Tabs in your browser (If you are using Chrome, press "cmd + T"), and upload images into the respective sets at the same time.
1. Upload all your images into a single set (you can use the default Highlights set), once the upload process is complete, you can select images to move or copy to an another set.
2. Create your set names before beginning the selection process:
3. To select multiple images at once, click on the thumbnail of the image, hold and drag across images you would like included in your selection. You can also hold the shift key and click to select multiple rows of images.
4. Once you have made your selection, you can move the images to the desired (already created) sets. Click the Move/Copy button, and select which set you would like to move or copy the image to.
Repeat this process until you have moved all your pictures to their desired sets.