We used to be able to change the group - prior to the, shall we call it, Recode?
There is no longer a way to change group except by adding an ID.
When forming an Observation WITHOUT an ID one is faced with having to add the Group - anything goes but it becomes impossible to change once the Observation is live. I am not certain what the default Group is but it is easily tested.
Generally speaking the Dictionary-to-group is accurate.