Sia will be cutting a hefty check to her estranged husband Dan Bernad ... and it’s all for child support, paid on the first of each month like clockwork. TMZ’s obtained docs showing Sia agreed to fork over $42,500 a month in child support to Dan Bernad starting April 1, 2026. The custody split is locked in too -- with the couple sharing legal custody and splitting up holidays ... Hanukkah and Father’s Day are going Dan’s way, while Sia keeps Christmas, Easter, and Mother’s Day. As we told you,