Hello parkjc02,
Find My is a great feature, and we know how important it is to ensure the correct device is sharing the location. It sounds as though you’ve walked through the steps outlined in the article below to set up the Apple Watch for your child.
Set up Apple Watch for a family member
When it comes to choosing which device shares the location with family members and within the Find My app, you would want to follow the steps in the following article.
Share your location with your family
If you’re unable to change which device is sharing the location, you may have to disable Content & Privacy Restrictions for your child’s Apple ID. Disabling Content & Privacy Restrictions would be temporary, and can be enabled again once you’ve chosen the Apple Watch to share the location from. The article below can help with disabling Content & Privacy Restrictions.
Use parental controls on your child’s iPhone, iPad, and iPod touch
Take care!