Are you in a big company/mnc or sme? For sme, I would feel a little bad because they don’t have as much finances/buffer for multiple pregnancy’s back to back. Do you have a close relationship with your boss? Have a direct chat about the third potential maternity leave and most fair thing to do is give them a heads up warning as soon as you find out you are pregnant (instead of waiting for the usual inform after first trimester). So there is ample time to plan for handover or maternity cover