Auto body advice please A family uses us for our free estimates! Then they use out estimate at their chop shop?

This family will not share the insurance information because the veh does not belong to them! They have a huge family including cousins. This is not only a waste of our estimators time, its insulting! How do we in a nice/legal way say sorry we cannot write estimates for you, any of you? They never have us complete a repair, they use our estimate and do it themselves at their chop shop...