JayDee Tas The first lesson of grandparenting is that how our grandchild is brought up is nothing to do with us. Beyond Grandma's rules in Grandma's house. Such as 'food and drink stay in the kitchen', the child's upbringing is entirely in the hands of the parents, you can only interfere if the child is at real risk of physical harm.
If they are disorganised that is their business, nothing to do with you. Do not get involved.
DS and DDiL are in their 50s, they are both academics and still live like students. They are not tidy and they have brought their children up very differently, but at 15 and 12, I have two happy secure grandchildren, both doing well at school, although DGD, the one tidy one in the house does fantasise of having a house of her own that would be very tidy!