Can both parents control our child phone?

Hello AngelMom2019.

Thank you for using Apple Support Communities. Please check out the following resource here:

Types of Family Sharing members - Apple Support

It states the following:

Parent/Guardian: An adult member of the Family Sharing group who can help manage parental controls for children in the group. When the organizer adds an adult to the Family Sharing group, they can designate them as a parent or guardian.

If you've properly set up Family Sharing, which includes your child and you're set as a "Parent/Guardian", you should be able to manage your child's parental controls. Just in case, we have a few more resources we'd like to share with you:

Set up Family Sharing - Apple Support

Set up parental controls with Family Sharing on iPhone - Apple Support

Use parental controls on your child's iPhone, iPad, and iPod touch - Apple Support

Create an Apple ID for your child - Apple Support

We hope this information is helpful. Best of luck.