Any one on a 457 visa must be paid the same as an Australian, if not report the company. So they will be on the same Qlink award.
South Africa has some smart folk, I assume only both pilots are male. I don't know if they are married to a professional with an occupation on the skills shortage list that qualify for a 457 visa, certainly possible from my understanding of SA.
If the partner of the pilot is issued a 457 visa, the pilot is also issued a 457 visa with full work rights (any kids too). More than half 457 visa holders in Australia are partners and siblings not skilled workers.
So things may not be as they seem, what do your partners do for work, is it a Skilled Shortage area?