A question that I'm often asked in the course of children disputes is whether or not each parent has a right to know the other's address. The answer is that there is no rule that one parent must disclose their address to the other. This comes as a surprise to some parents, who believe they have a right to know where their children are living. Having said that, courts do usually prefer addresses to be disclosed unless there is a good reason why they should not, such as a history of domestic violence or harassment. If the address is not disclosed then there should obviously be some means of communication open between the parents, such as telephone or email, save in exceptional circumstances.
What if the 'absent parent' wishes to apply for an order in respect of the children, such as a contact order, but does not know the whereabouts of the children? The answer is that they can apply for an order under section 33 of the Family Act 1986 requiring "any person", such as a relative, to disclose information to the court as to the whereabouts of the children. Note that the order directs that the information be given to the court, and not to the parent. Once the whereabouts of the children is known, the original application can proceed.