During that era, Mix 106.5’s audience share went like this:
S1/1996: 7.5% (5th; 3rd FM)
S2/1996: 7.5% (4th; 3rd FM)
S3/1996: 6.8% (5th; 4th FM)
S4/1996: 6.8% (5th; 4th FM)
S5/1996: 5.9% (8th; 5th FM (beaten by JJJ))
S6/1996: 8.4% (5th; 4th FM)
S7/1996: 8.0% (5th; 4th FM)
S8/1996: 7.1% (7th; 4th FM)
S1/1997: 7.6% (6th; 4th FM)
S2/1997: 7.8% (5th; 4th FM)
S3/1997: 7.8% (6th; 4th FM)
S4/1997: 6.9% (7th; 4th FM)
S5/1997: 7.5% (7th; 4th FM)
S6/1997: 7.8% (7th; 4th FM)
S7/1997: 8.7% (4th; 3rd FM)
S8/1997: 9.3% (4th; 3rd FM)
During that time, 2WS was generally at around #2 or #3 FM, whilst 2Day was well ahead, battling with 2UE for the #1 overall spot.
From what I can see on the figures, the changes that occurred on Mix would’ve happened after Survey 4 of 1997, as its audience share increased steadily from that point on, ultimately reaching 10.7% in Survey 6 of 1998, in which it came 2nd on among the FM stations. As for 2WS though, its audience share fell from the beginning of 1998, down from 10.5% in Survey 1 to 7.1% a year later (S1/1999), by which point it had evolved from a “Best Songs of All Time” to a “Classic Hits” format.