Joined: 26 Apr 2004 Posts: 4650 Location: Raleigh, NC, USA
You can't. You are only allowed one version per generation. Doing otherwise would defeat the whole concept of generation data groups.
Normally, a new version is created as a replacement for the old version, usually as the result of some fix to the data.
The only suggestion I have is to make a copy of the original version first, to either another GDG group, another generation within the same group, or to a plain sequential dataset, then do your update to the version.