Off for a day out today for DD's birthday and have invited her friend to come with us. She's an absolutely lovely kid and I'm more than happy to have her come along, she comes out with us quite a lot.
Have just had a text from her mum to ask if we can also take her sister with us too as she (mum) isn't feeling very well today and it would really help her out.
Normally, I would be happy to help but I really don't want to take her sister too. She used to come round 2/3 years ago when the girls were younger but I had to put a stop to it as she caused so much drama. She constantly argues with her sister, makes her cry, kicked the dog while he was asleep to get him to move out of her way 
and was consistently unkind to my DD too. She's 12, very sullen and generally would make the day miserable for everyone.
She also, I very strongly believe, took some things from my house and money from my purse. I didn't tell her mum at the time (I know I should have) because she was going through a horrendous time at that point and didn't want to make things worse. I've since found out that she did the same at another friends house (who did tell mum so she is aware of the problem). After the dog and money incidents (on the same day) I just put a stop to her coming round by generally engineering it that way. (So I basically took the easy way out).
I feel like a bitch for not helping this woman out if she's not well but I really don't want to take this girl along too and I'm well aware that I sound like an utter cow for saying this about a 12 year old kid but it's really going to spoil the day for DD and her friend. I also don't know what to say to her mum.