Yes, when I read this I thought the best thing would be to pass on that AC called with a reminder that the MOT is due on her car. And if she says - Huddy can you arrange that? Then you could just pleasantly - I'll leave that to you as you have the car now.
To me that's cooperative and gently conveying the message that you won't be picking up on stuff like this for her. If she pushes back with something like - oh, so you're not even going to help me with the car now? Then you could respond along the lines of - well, now we're S and you have the car, it's best you arrange that direct with them.
Hope this helps x
T 13 M 7 Me 48 H 46 SS 15 BD 7.14 PA D final 5.16 (H filed)
We receive & we lose, and must try to achieve gratitude & embrace with whole hearts whatever of life that remains after the losses - Dubus