I thought they dropped the “ATN” name earlier in the 90s
Western Australian Television History (WA TV History) » Blog Archive » Update on documenting our TV heritage suggests that Quintex had purchased both 7 Perth and 7 Adelaide (the former owning the latter at the time) in 1988 - and was part of the Seven Network when listed on the stock exchange after the Quintex collapse [@TelevisionAU may be able to confirm]
News had some investment at some point in that period - the ABA investigated concerns over control of Seven by News after concerns from Optus
I forgot about that - good pickup