Panama City is 14.5 hours behind Adelaide

There is no standard 8-to-6 overlap. Someone joins early or late.

The 14.5-hour offset between Adelaide and Panama City means there's no point hunting for a 9-to-5 overlap — there isn't one. Expect compromise: someone in Adelaide or Panama City will need to take the call outside the usual 9-to-5, so share that load. Remember that Adelaide shifts for daylight saving and Panama City doesn't, so recalculate the overlap after each clock change.