Adelaide is 12.5 hours ahead of Montevideo
There is no standard 8-to-6 overlap. Someone joins early or late.
Montevideo and Adelaide are 12.5 hours apart, and that gap is wide enough that their normal 9-to-5 workdays never quite touch. If you meet regularly, fix one off-hours slot and rotate it between Montevideo and Adelaide so the burden doesn't fall on one team. Because Adelaide and Montevideo don't both observe daylight saving, plan to re-check the overlap around March and November.