We want to take our grandchildren (9, 5, 3yrs) and their Dad…

You don't need the permission of the Mother to take the children interstate. You only need her permission if the children were travelling overseas.

As long as the time that the children are away does not interfere with the time the Mother or grandparents are to spend with the children in a court order, you don't need their permission.

If you are seeking to take the children away, during a time when they are due (under a court order) to spend time with the Mother and/or the grandparents you would need their agreement to make alternative arrangements to make up the time they miss at another time. If they don't agree and you go anyway, then the person who misses their time wtih the children under the court order can file an application for contravention and if found guilty of breaching the order, your son can have penalties imposed against him such as an order to attend a parenting program, community service, or a fine.

You could try to file an urgent application in the court, but usually before commencing proceedings in court you have to have a certificate from a family dispute resolution provider. In urgent situations you can ask to have your matter heard without a certificate.

If the time interferes with the time under a court order that the children are to spend with the Mother and/or grandparents you should immediately contact your closest family relationship centre (find it at www.familyrelationships.gov.au ) and organise urgent free family dispute resolution with the person (either Mother and/or Grandparents) whose time is going to be effected.