Rio de Janeiro is 13 hours behind Melbourne
There is no standard 8-to-6 overlap. Someone joins early or late.
Melbourne and Rio de Janeiro are too far apart in time (13 hours) for their workdays to line up during regular hours. For anything urgent, agree on an early-morning or late-night bridge hour in advance so nobody's caught off guard. Just remember Melbourne changes its clocks for daylight saving and Rio de Janeiro doesn't, so confirm the overlap whenever the seasons turn.