What I understand is that you are able to reach 2 3 and 4 from the bgroup IF, but not from 1 subnet. Is that right?
Sounds to me like a routing issue, what Steve mentioned in his initial post. Do the routers and Firewalls that sit between the SSG and 2,3,4 have their default route pointing to the SSG? They are probably routing the return traffic out some other interface.