You do not provide much background, but I presume from your question that there is an existing custody order, but it states that the child lives with your ex. If so, the easiest solution would be to do a stipulation and order altering custody and setting support. If you can't get that cooperation, it is in the form of a motion asking for recognition of de facto change of custody and have support set by the court. For background, see http://willicklawgroup.com/child-support/ and http://willicklawgroup.com/child-custody-and-visitation/.
Answered on Jun 16th, 2015 at 12:02 PM