My assumption is that both counsel have restricted themselves to the small proportion of the chat that might have some relevance to the character or truthfulness of witnesses.
Faced with possibly thousands of pages of seven(?) way conversations even working out who said what and when might take weeks. I'm not sure that NC would have had time to do much more than a sampling - how could one tell that all of the comments relevant to character or truthfulness have been found?
Also - there must have been many, many other whatsapp groups featuring SP, DU et al. but these all seem to have been kept private.
If whatsapp messages are fair game then were are DU's private groups?
I'm guessing that the point is that this set of messages have been voluntarily released.
My opinion, given the level of general sniping, bitchiness and classism at Fife, is that many of the players will have conversations that are much more incriminating than the one released but have chosen not to publish.