You are not required to file a Form 990 return if your subordinate organization is included in a group return. A subordinate organization must consult with the parent organization to include the organization in the group return and authorize it.
An organization has to make sure it is included in a group return before deciding not to file the Form 990 return. If a subordinate organization is not included in the group return and has gross receipts of $200,000 or more, then the organization has to file a Form 990.