Plumber will have to do all the work even putting in 'check' meters and then the water board will replace the check meters with their official ones.
Or at least this is how it was described to me some time ago for NSW.
In the end we simply left the main waterboard meter in place and manually charge each tenant on what is used via the tenants check meter. Work OK as long as the PM remembers to read the meters. We have managed to do this with most of our blocks and also a granny flat set up but one block of 7 units frustrates me as there is no clear location to put meters for more than half of the units in the block.
Best to give your local authority a ring to get guidance.
Cheers