At the moment we are just working with one to one lessons (unless the children are siblings working at a similar level). We have tried group lessons in the past but they didn’t prove to be as effective as one to one lessons.
They can often lead to bickering between siblings. The other thing I have found is that if one child is consistently stronger than the other it can leave them feeling deflated and incompetent. It is also easier to work with a person’s personal, specific needs on a one to one basis.