Legal Question in Family Law in California

You can't. There is no such thing as a permenant custody order between parents. Custody between parents can be reviewed and changed by the court any time until the child turns 18.

More facts are warranted to understand your question. If you need to get a court order to reflect your custody and timeshare, then you must file and serve a motion with the court requesting the order. Timeshare and custody will always be a moving target based on the child's needs, living arrangements, etc...