A Collection can be expanded or updated by adding more assets at any time. When you want to add assets to a Collection, follow these steps.
Add Assets to Collection
Go to the assets you want to add
Select the desired assets
Click the Collection icon in the toolbar at the top of the browsing pane or press Shift + C
Select the Collection from the dropdown or, if you have a lot of Collections, search for it by name in the provided search bar.
Pro Tip: If the name of the collection you'd like to add your assets to is used multiple times in your account, try searching for its parent collection for faster search results.