When you are part of a Microsoft family, your family members with Skype accounts are automatically added to your Skype contact list. A group chat conversation called “My Family” is also created with all of the members of your family who are on Skype.
You can remove family members from your contact list just like any other contact. Your “My Family” group behaves like other group conversations and does not sync members back to your Microsoft family. If you like, you can leave a family group just like any other Skype group chat without impacting family membership.
If you see that a family member is missing from your group, check to make sure that they have a Skype account that matches their Microsoft family account address.
Learn more about Microsoft families here.