The whole Isabelle being left alone to look after the others thing, personal I think is irresponsible.
Yes she’s 15 nearly 16 and it was at night so they maybe asleep but I don’t mean to be rude but Isabelle is not a normal 15 year old she’s a nervous wreck half the time due to her parents.
God forbid there was an emergency groomer granny is quite far away they don’t know the neighbours. Plus she will be worried about her mum. Personally that’s a lot of pressure to put on Isabelle especially considering how sheltered her life is, I don’t think she would know what do in a emergency.