They do not contact the previous partner (s). I suspect it is just to ensure that your current relationship is legal. Common law relationships break up all the time. I would include a short note explaining that the relationship broke down and that it is no longer valid. No need for great detail, just something simple like. XXX and XXX mutually ended their common law partnership on XXX due to relationship breakdown. This will avert the question, if it comes up later on, about when the relationship broke down. Usually if it's a marriage you would include the divorce certificate so that requires less explanation.