I recently changed my developer account from company to individual. I have successfully transferred my applications, apart from the application groups.
I cannot see anyway of transferring the existing app groups and my thoughts are that if I create a new app group, existing users will:
So I just spoke with Apple on the phone - they were awesome at helping and we found a solution.
Let's assume account A is the old account and B is the new account that you want to transfer the app group to.
Simply delete the app group from account A and recreate it in account B with the exact same identifier. Problem solved :D Thank you Apple!