Dbs points earned on different DBS cards are pooled together and expiry tracked separately (Woman's card 1year, altitude card no expiry). Paying miles conversion annual fee allow you to convert DBS points to miles unlimited number of times in a year from the point that the fee is paid. The DBS points that expire first will be converted to miles first.
DBS cards does not have negative balance. If there are not enough points for refunded transactions, it goes to 0.
For the bonus 9x points for DBS Woman's Card credited the following month for online transactions, if there are transactions made and refunded transactions, DBS will take the positive amount to award the bonus 9x points the following month. Example: Made transactions of $4000 and there are $2000 refunded transactions, you will get bonus 3600 points.
If there are refunded transactions, no bonus 9x points will be awarded. It will not be reversed.