Can someone tell me why my mother in law won't ever visit our house without her daughters daughter (her granddaughter). We have 2 children that they rarely see. We invite mother and father in law over for dinner or breakfast and they constantly turn up with their other granddaughter. It is driving me insane. Nothing against their granddaughter but I just find it so rude and odd? Any ideas please? Husband also baffled and can't work out why they keep turning up with her?!