Hello Client , I can Help you with this issue , if u post a message or attachments to your private Group , it will automatically forward the message or attachments to. another group . i can do it . actually i already did it in my local , i will show you ,if needed .
i have video of it ,share your email or Skype or WhatsApp Number, i will send it to you so that you can confirm that your requirements will be satisfied with me