Andrew 5858015:
Because this "group" can't be open in a single separate page to see all the Forums included it. Right?
You're right, there's no way to open the list of forums inside of such "group" - but honestly, I didn't get the idea of why you would like to open it that way.
Andrew 5858015:
Or there is a way to do it?
There could be a way to code some add-on/extension/hack; but I'm not sure how efficient and expensive in development it would be.
Andrew 5858015:
Is there can not be the Groups of Forums, can the Topics have some connection with each other? Maybe to show on the top of the page of one's topic - links to the topics with similar subjects? It could be a kind of solution for this problem.
For some forums, I have coded an add-on called "Similar Topics" - the list is displayed beneath of the primary topic and it tries to list topics of the similar subjects (based on a special mySQL request) - this is the only thing I could suggest for some small fee for your purpose, too.