trade discount and GST

our Head office at chennai. Branch office at Hyderabad. Earlier we transferred goods to Branch by paying Excise duty only. No sales tax VAT paid. Now we pay 12% GST at our Head office and send goods to Branch.
At our Branch they sell goods at the same rate to public. Further they sell goods at 30% discounted rate to our Distributer. Further they sell goods At 25% discounted rate to our shareholders. Our branch sell goods at decreased value to distributer and shareholders and collect less GST from them.
In view of this our company get loss in GST payment. How to avoid this? please inform me