You are clearing sharing a single AppleID between multiple Users. Sharing an AppleID with others is a very bad idea.
Your granddaughter should have their own AppleID - in fact, every user should have their own AppleID. This is essential to maintain separation of activities and to avoid unintended sharing of information and data. Done properly, you’ll not have any issues with content related to your child appearing on your own devices - or vice versa.
You may find this information to be helpful with setting-up an AppleID for a minor - and in considering appropriate controls while continuing to share Apps and paid Apple services if you should choose to do so:
Apple for Kids - Official Apple Support
Help your child set up an iPhone, iPad, or iPod touch - Apple Support
Family Sharing and Apple ID for your child – Apple Support
Use parental controls on your child's iPhone, iPad and iPod touch – Apple Support