To upload more images to an existing folder, select your Collection, and then Folder you would like to add images to. Next, click on “Upload photos” at the top right of your Dashboard.
This will open the uploader window, and you can either drag & drop or browse your files to select the images you want to add.
Woohoo! You've added even more beautiful photos to your Collection. 🤗
Other Help Center Articles:
Can I Replace Images in My Collections?