Add photos and videos to shared albums in iCloud
At any time, you can add more photos and videos to a shared album. When you do, subscribers to the shared album receive a notification that new items have been added.
In the Photos app on your iPad, tap a shared album.
Tap the Add button .
Select the items you want to add, then tap Done.
Enter a comment, then tap Post.
Videos added to a shared album can be up to 5 minutes long.