Family sharing iCloud+

When joining your family sharing group did she accept the offer also to join your (shared) iCloud+ space?

If not she can do this at any time. Apple has instruction for this in the section of Share iCloud+ with your family - Apple Support called Switch from your personal iCloud+ plan to your family plan. Using her device follow these instructions:

On your iPhone, iPad, or iPod touch 

In iOS 16 or iPadOS 16 later:

1. Go to Settings > Family.
2. Tap Subscriptions.
3. Tap iCloud+.
4. Tap Use Family Storage.

In iOS 15 or iPadOS 15 or earlier:

1. Go to Settings > [your name].
2. Tap Family Sharing, then tap iCloud+.
3. Tap Use Family Storage. 

On your Mac

In macOS Ventura or later:

1. Choose Apple menu  > System Settings, then click Family.  
2. Click Subscriptions, then choose iCloud+. 
3. Click Use Shared Plan. 

In macOS Monterey or earlier:

1. Choose Apple menu  > System Preferences, then click Family Sharing.  
2. Click iCloud Storage.
3. Click Use Family Storage.