5 year old that intentionally poops in a diaper

     I am babysitting a little girl who poops in a diaper.  Now she doesn't always wear one.  She pee pees in the toilet but when it is time for her to poop, she has to put a diaper on, poops in it and makes whomever is taking care of her, clean her up and put her regular underwear back on.  I think it is a behavior issue.  She isn't the sweetest, unfortunately.  How do I go about getting her to go to the bathroom right?  If she was my child, I have the answer of what I would do but I am just her after-school babysitter and it is a touchy situation with her mom (great woman but I think she is embarassed by it).  Help!

[KillingtonRob]

if you are still babysitting her and still of this problem....i know that this is a concern and i think your are right but you can't do nothing about it and it's up to her parents....well you can talk to her Mom and say here is what i think but after you say what you think..then you need to say whatever you decided to do i will back you up 100%