Restricting calls on apple watch in family mode

I bought an apple watch for my daughter to use. She is 8 and so doesnt need a phone, but we would like a way to track her and be able to contact her or have her contact us in an emergency. Unfortunately within 1 hour of her number being active, she has already received spam calls. How do we restrict incoming calls to those on her contacts? This should be a basic feature of the family mode as the last thing you want is your child or older parent receiving spam, inappropriate or scam calls