Group plans

Been trying to set up similar group plan for family members who are leaving O2 and it’s very difficult to set one up with Smarty. 
I want to pay all the bills and receive all the notifications etc as I do at the moment with O2. This is impossible so far with Smarty. All together we could have 7 members of this group. When I start entering their details (such as PAC etc) the Smarty system recognises my Smarty email and stops me. I’m directed to ‘add’ sims instead. The offers here are completely different to those advertised on Smarty Group Plans adverts. This is very annoying and frustrating. Why can’t I just switch these sims across from O2 - why is it so difficult?