Suck up what you can financially but don't do what she is supposed to be doing on her own. She's supposed to pay her car insurance payment to you? You think she needs reminders? She does not. You are screwing up and putting yourself in the role of parent when you remind her. BAD MOVE. She knows the payment is due. If she doesn't pay, what happens? Her coverage lapses. That's the real world. Let it lapse.
If she hasn't paid it, and it causes you financial difficulty to do so for her, drop her car.
