A regular lunar month and its leap-month counterpart are different dates. Preserve the original record before starting a chart: lunar year, month, day, whether it is the leap month, and the known birth time.
Make the Leap-Month Status Explicit
Write 'leap fourth month,' for example, rather than only 'fourth month.' A year may contain both. Confirm the calendar type with the person who supplied the record instead of inferring it from a familiar-looking date.
Check the Converted Calendar Date
After conversion, compare the displayed Gregorian date with a reliable calendar reference. If the interface does not clearly distinguish the regular and leap months, do not submit a guessed date merely to continue. Keep the original details visible for correction.
Separate the Date From the Charting Rule
A Zi Wei calculation may apply a particular convention to leap-month births. That convention is separate from identifying the person's actual birthday. Ask which rule is used and whether it affects the chart. Changing the interpretation convention must not silently rewrite the birth record.