Does the overall listing have to be mother and child?

That's not true. The overall listing of parent and subsidiary companies means that the controlling shareholders of listed companies and their subsidiaries are listed together in a holistic manner. However, in addition to the overall listing between parent and subsidiary companies, other types of enterprises can also participate in the overall listing, such as multiple member companies and consortia under the group company. Parent-subsidiary company means that one company (parent company) owns all or most of the shares of another company (subsidiary company) and controls it in management and finance.