v tired so this will probably be incoherent, but DD (8) had her friend over for a play date yesterday. they wanted to play with/draw on a big empty cardboard box, which i said was ok as long as they took it into the garden. i have baby twins so went into the other room to feed them, DD ran in saying '[friend] won't listen when i tell her to stop'... went outside to find that the friend had gone into the conservatory and found the bits of styrofoam that i'd taken out of the box and was shredding them into approx. 1 billion tiny pieces and strewing them over the garden and conservatory. i told her to stop and she said 'it wasn't me, your cat did it!' while still shredding the plastic! i put DTs in playpen and started to try to sweep up... heard DD yell to me again and went into kitchen to find the friend had climbed up on the counter and got down a bottle of fish oil tablets and literally poured them all over the floor, and was squishing them one by one. i explained through gritted teeth that crawling babies and tablets on the floor was a dangerous combination as they could swallow one and choke, to which she responded by laughing and did an impression of a baby choking. her mum arrived not too long after that and i mentioned all of this (in a fairly casual way) and got 'oh yes she does that sort of thing at our house too' 
yesterday evening i then discovered that she'd scrawled something illegible on DD's bedroom wall, and had also pulled the sheet off DD's bed and written her name in pen on the mattress! i'm just a bit shocked at how poorly behaved this child is. never want her in my house again to be honest. AIBU?