can an album i share with someone be re shared by that person to somebody else?

Hi From_the_tree,

It sounds like you would like to know if your cousin can invite other relatives to share the album you shared with her. You are the only person who can control who sees your shared album. In the article you reviewed - How to share albums in Photos on your iPhone, iPad, and Mac - you learned how to invite people to your shared album:

"Invite more people

1. In Albums, select a shared album that you created.
2. Go to the People tab.
3. Tap Invite People.
4. Enter the names of people that you want to share this album with.
5. Tap Add.

You can even share albums with friends and family who don't use iCloud. Just open a shared album that you created, go to the People tab, and turn on Public Website. Your photos publish to a website that anyone can see in an up-to-date web browser."

If you wish, you can have your cousin share the public website link with additional people. But you still control the content of the shared album.

Alternatively, if your cousin follows the instructions in the article above to save the photos you shared to her own Photos library, then technically she could create a new shared album and invite as many people as she wants to the newly created album that is attached to her Apple ID in iCloud Photos.

Best regards.