Google-groups – How to print out an entire thread in Google Groups

While it's not possible to achieve that through Google Groups web interface, because it is by design, you can do it if use your Gmail to keep up with the group. You can setup your group to receive e-mail on every post and the by replying to that mail and changing the subject, will force the group to create a new post. So in both places you can see your threads correctly.

Also it's a good idea to create a special filter for it to Skip inbox for example.

You can report to Google by clicking on the "settings" icon on the top right and from the drop down menu selecting the option "Report an issue about Google Groups". I have the same problem and already did that. Hopefully the more people doing the same the more chances we will have to be able to get a reply.