I'm no expert on the subject (and to be honest no one is because all the rules seem to be ad-hoc)
But heres what i know.... The company has to show to the govt that it has business (or contracts) and to support or run that business, it needs to import manpower. That's how they get a quota of rp allocated.

Life for the family is perfect here.

As for how long it takes to get the family visa... 1 week if your company is run by reasonable people. But if the PRO is a sucker it could take 2 months to never
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Quidquid latine dictum sit, altum sonatur.