Same group, multiple group chats - How to fix?

I'm in a group chat with 3 others. We all have iPhones. About a month ago, a new group chat was created with the same group. I deleted it, but it came back. 3 of the 4 of us experience this problem. The other guy has no idea what we're talking about when we say "this is driving me crazy." Many others seem to have also experienced this problem: > "iOS 8 creating multiple group messages with same recipients" (Official Apple Forum ) There is no answer in the above thread. How can we fix this issue?