Dallas is 10.5 hours behind Chennai

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

Chennai and Dallas are 10.5 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 Chennai and Dallas so the burden doesn't fall on one team. Remember that Dallas shifts for daylight saving and Chennai doesn't, so recalculate the overlap after each clock change.