Looking at Singapore Airlines' KrisFlyer Terms and Conditions, it appears that the answer to your question is "Neither of you will earn miles for the portion of her ticket that was charged to her credit card."
Singapore Airlines' KrisFlyer webpage contains this text:
For Mix KrisFlyer miles and cash bookings, the number of KrisFlyer miles, Elite miles and PPS Value you earn will be in proportion to the amount that you've paid with your credit/debit card (excluding taxes). If the full amount is paid with KrisFlyer miles, no KrisFlyer miles, Elite miles and PPS Value will be earned. Read more in FAQs.
The FAQ cited above contains this question on Page 2:
Will I earn KrisFlyer miles, Elite miles, and PPS Value if I mix KrisFlyer miles and cash for my:
The page goes on to list different factual scenarios in which miles and money are used to obtain tickets. Subsection (b) applies here:
(b) fare on Singapore Airlines or SilkAir for my redemption nominee(s) only?
No, you won’t earn miles when you’re not a passenger in the same booking. If your redemption nominee is a KrisFlyer or PPS Club member, he/she will earn KrisFlyer miles, Elite miles and PPS Value on eligible fares. KrisFlyer miles, Elite miles and PPS Value will be earned in proportion to the amount (excluding taxes) that you have paid with your credit/debit card. [emphasis added]
Thus, you must be a passenger to earn miles. Your nominee will earn miles only if the money part of the ticket was paid for using your credit card, not hers.