You can invite family or friends to your Series in the Chatbooks app so they can help add photos and captions to your books.
How do I invite someone to my Series?
Open the Chatbooks app
Tap into your Series subscription
Tap the Settings (gear icon) in the upper right corner
Tap "Contributors"
Tap "+ Invite contributor"
Tap "Invite from contacts," select who you want to add, then tap "Add contributor"
A text message with your invite link opens. Tap send.
You can also tap "Copy invite link" to share your invite by text, email, or another app.
If you see "Permission Needed," tap "OK," then allow Chatbooks to access your contacts in your iPhone settings.