They were both members of Duncan Laing's elite squad.
Wilson competed at the Atlanta Olympic Games in 1996 and van Welie won a silver medal at the Edinburgh Commonwealth Games in 2002.
Clearwater (15), a year 11 pupil at Bayfield High School, broke five Otago short course records at the 26th annual Neptune Swimming Carnival at Moana Pool at the weekend.
She is a backstroke specialist and three of the records came in her own girls aged 14 and 15 age group.
But the most significant records of all came when she broke two open women's records in the 100m (1min 05.77sec) and 200m (2min 18.13sec) backstroke.
Clearwater has shown the dedication that is needed to reach the top.
She must get up when the alarm clock rings at 3.50am each morning.
She lives on a sheep and cattle farm at Cape Saunders and it is a 40-minute drive to Moana Pool for morning training with coach Gennadiy Labara that starts at 5am.
Clearwater started serious swimming nearly 30 months ago when invited to join Labara's Otago Swimming Coaching Academy (Osca) squad.
It has been a successful and record-breaking few months for Clearwater.
She set an Otago short course record of 2min 18.28sec for the 200m backstroke at the New Zealand summer championships in Christchurch in December and broke three short course Otago records at the South Island championships in Christchurch in September.
The Neptune carnival was also significant for the Osca training squad, which reached an important milestone when Han Zhang (Neptune) broke the Otago boys aged 10 and 11 200m butterfly record with his time of 3min flat.
It reduced the record set by Hamish McCulloch (Waves) three years ago by a seven seconds.
It was the hundredth Otago record broken by swimmers in the Osca squad since Labara became coach 30 months ago.
Osca swimmers broke 16 records at the weekend and have now broken 108 Otago records.
Zhang held his record for just three minutes, before it was broken by Ronald Poon (Neptune), another member of the Osca squad, in the next heat, in a time of 2min 48.08sec.
Poon broke eight Otago records at the Neptune carnival.
The other Osca swimmers to break records were: Cameron McMahon (Neptune), boys aged 12 and 13 50m freestyle (26.21sec), Matthew Glassford (Neptune), men's open 200m breaststroke (2min 16.30sec).
The other significant performance by Osca swimmers at the weekend was in the men's open 400m freestyle when its two swimmers broke the 4-minute barrier for the first time.
Glassford won in 3min 59.70sec and Nick Tyrrell second in 3min 59.85sec.
The other six records were broken by members of Punch Tremaine's squad.
Nicole Ruske (Neptune) set a mark in the girls aged 9 and under 50m backstroke (41.92sec) and older sister Aleisha Ruske (Neptune) broke five records in the girls aged 10 and 11 grade: 50m (29.96sec) and 100m (1min 06.21sec) freestyle, 50m (33.26sec) and 100m (1min 14.69sec) butterfly and 100m individual medley (1min 17.42sec).
• Otago records
Broken at the Neptune carnival
Eight: Ronald Poon
Five: Lil Clearwater, Aleisha Ruske
One: Matthew Glassford, Nicole Ruske, Han Zhang, Cameron McMahon.