Is there a way to edit a existing design group?
Is it plan to support this?
Please explain better so that we can understand what you actually mean. Use exact terminology, too – KiCad doesn’t use the word combination “design group” as far as I can remember.
Yes, you are right.
The correct terminology is “design block” (my mistake)
I created some specific blocks in a library. Now I’m looking how to change details without creating a new design block.
Have you tried to save with the same name?
You can overwrite an existing design block, or delete it and create a new one with the same name. Design blocks are pretty new and a lot more features are coming in v10. (PCB design blocks, updating them, etc.)
Save as new works, of course.
But in this case you must fill the form with all the required informations again. An edit button would be handy.