I am so glad they are doing really well. I wouldn't worry about the grooming some rabbits groom one another m ore than others. I think it should be ok to increase their space at the weekend. Take some of their bedding with them so it smells familiar. Sometimes, when you put bonded rabbits in a different environment there is some humping as they have to reestablish the dominance thing. So if you let them do that for a short time then intervene, it should calm down fairly soon.