My daughter can't remember her password and she is locked out of her phone. Can we unlock it if we have family sharing?

See this document If your Apple ID is locked or disabled https://support.apple.com/en-us/HT204106 "If you or someone else enters your password, security questions, or other account information incorrectly too many times, your Apple ID automatically locks to protect your security and you can't sign in to any Apple services.

If you use security questions with your Apple ID, or if you don't have access to a trusted device or phone number, go to iforgot.apple.com. Then you can unlock your account with your existing password or reset your password. After multiple unsuccessful attempts to unlock your account, your Apple ID will remain locked and you can try again the next day.”

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Also see See If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled  https://support.apple.com/en-us/HT204306, especially the section entitled Remove your passcode. 

If you don't have a computer as mentioned in Remove your passcode, then "borrow one from a friend, or go to an Apple Retail Store or Apple Authorized Service Provider." Of course the last option usually is not available now.

Later the document says: "If you can't update or restore your device using recovery mode, or you can't use recovery mode because of broken or stuck buttons, contact Apple Support. Then follow the steps to set up service for your iPhone, iPad, or iPod touch."

If she waits about 24 hours, she should be able to try again.

Enter the Apple (iCloud) ID and click Forgot Password.

Apple ID - Manage            

Apple ID – Forgot Password