As long as you have a membership account, you can create albums and add pictures from
- Your own albums of pictures
- Albums of pictures shared with you as a contributor
A single picture can be in any number of albums. As long as you either own or you've been added to it as a contributor, you can add it to any album of your own. The owner will always know who has added the picture to their albums by looking in the Contributors tab of the share panel.
Note that pictures owned by, or shared with, others may continue to change as others add content. Similarly, pictures you added to your albums but owned by others may be removed from your albums if the owner removes them. Privacy is controlled at the individual picture level.