Grouos

I successfully created 4 Groups each with 20 recipients. When I tried to creat fifth group,. It did not work. Hence I uninstall Skedit and reinstall again to create the 5th group and. Send the mesage. Can somebody advise how to manage grouping because, I have approximately 2,800 participants in whatsapp and total individuals in phone book of 5,000+. I will send sms to whose without whatsapp. Plz help