Children who move due to a court - ordered change in custody due to separation or divorce, or the serious illness or death of a custodial parent. (leg.state.fl.us)
Second order change does happen — but mostly through major crisis — and even then there is no guarantee that the outcomes will be constructive. (dotearth.blogs.nytimes.com)
Once you have filed the correct forms and paid the required filing fees, you will be asked to appear at a court hearing to explain why you want the custody order changed. (info.legalzoom.com)