Change Communication Limits settings in Screen Time on Mac
Use Communication Limits settings in Screen Time to limit communication with others. Limits apply to phone calls, FaceTime, Messages and iCloud contacts. Communication to known emergency numbers is always allowed.
To change these settings on your Mac, choose Apple menu > System Settings, then click Screen Time in the sidebar. (You may need to scroll down.) Click the Family Member pop-up menu on the right and choose a family member (if you’re using Family Sharing), then click Communication Limits.
Choose who the family member can communicate with during allowed screen time.
Contacts only: Allow one-on-one and group conversations during screen time only with people in the family member’s contacts.
Contacts and groups with at least one contact: During screen time, allow one-on-one conversations only with people in the family member’s contacts and allow group conversations that include at least one person in the family member’s contacts.
Everyone: Allow one-on-one and group conversations during screen time with anyone, including unknown numbers.
During Downtime, Allow communication with
Choose who the family member can communicate with during downtime.
Specific contacts: Allow one-on-one and group conversations during downtime only with specific people in the family member’s contacts. To specify the allowed contacts, click Select Contacts, then use the Add and Remove buttons to modify the list.
Contacts Only: Allow one-on-one and group conversations during downtime only with people in the family member’s contacts.
Contacts & Groups with at Least One Contact: During downtime, allow one-on-one conversations only with people in the family member’s contacts and allow group conversations that include at least one person in the family member’s contacts.
Everyone: Allow one-on-one and group conversations during downtime with anyone, including unknown numbers.
Note: The available options vary, depending on the current settings for allowed communication during screen time.
Allow contact editing
Let your family member edit their contacts in the Contacts app. Turn this option off to prevent them from editing their contacts.
You won’t see this option unless your family member has accepted your request to manage their contacts.
Manage [family member’s] iCloud Contacts
Request to view and manage your family member’s iCloud contacts.
Set up iCloud contacts management: Turn on Manage [family member’s] iCloud Contacts. A request is sent to the family member.
Stop managing a family member’s iCloud contacts: Turn off Manage [family member’s] iCloud Contacts.
Contacts
Manage your family member’s iCloud contacts.
See how many iCloud contacts your family member has: The number of contacts your family member has is shown.
Manage a family member’s iCloud contacts: Click Edit, then view, edit, add or remove contacts.
You don’t see the Edit button until your family member accepts the request to manage their contacts. Until then, Pending is displayed.
and Remove 
buttons to modify the list.