Explain why the addition would help
Have the child name the reason for inviting someone. “They are helping with Saturday’s project” is different from adding a friend simply because the button is available. Ask whether a separate conversation would be clearer. Avoid framing an invitation as proof of friendship that the new person must accept. Give them a way to decline without requiring an explanation in front of the group. A smaller conversation can remain useful without becoming a statement about who is included in every part of someone’s life.
Check the audience change
Before using the add-member control, review the platform’s current explanation of what a new participant can see and how other members are notified. If that information is unclear, use a new conversation for the new purpose. Do not test visibility by adding a person and asking them to report which private messages appeared. Talk about the general principle with a harmless example: information shared for a homework pair should not automatically move to a larger social group.
Make the new purpose clear
If the invitation is appropriate and accepted, introduce the reason for the group and any practical expectations. Do not post someone’s contact details to a wider audience to make the invitation easier. If a member objects, pause and resolve the question without making the child mediate an argument alone. Review the group when its original task ends. Clear membership choices can keep a useful conversation from growing into a stream nobody intended to join.