In Scotland the law says that you have to separate them at 8YO if different sexes - IF - there is adequate space and you are able to. I work with a housing asssociation and when we have tenants who have 9 and 7 yo kids we cannot re-house, then they could not be seen to be breaking the law as it is out of their hands till they can be re-housed. Lets face it, lots of people cannot afford to buy and there has to be a common sense aspect to this.
My own children are 7 yo boy and 9 yo girl. They have their own rooms but through choice have a sleepover in each others rooms on the weekend. The sofa bed folds down and they are like a wee married couple - in the purest manner of course. When we go in to tuck them in we often smile at the cute way they are together. When we go camping, although they could have a 'pod' each, they prefer to sleep in the same one.
Children don't think of things being wrong till its natural which is often way past the time the 'law' says.
There is absolutely nothing wrong with your grandchildren sleeping in the same bed/room till they think there is. Common sense prevailing of course.
