Hello Jentle72,
Thank you for using Apple Support Communities! I understand that you're experiencing some issues using FaceTime on an iPad with an Apple ID that you created for your child. You've come to the right place for help.
Is this an iPad that will be solely used by your child or will it be shared with others? The reason why I ask is that it sounds like you may be signed in to more than one Apple ID somewhere, or sharing an Apple ID which could cause your calls, texts, contacts, and other data to be synced across devices using iCloud. If the iPad will only be used with the child Apple ID that you created, follow the steps in the resource below to remove your personal information from the iPad:
What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support
After that, set up the iPad again using the child's Apple ID:
Help your child set up an iPhone, iPad, or iPod touch - Apple Support
Cheers!