I don't really see why you should sign any such thing. If the child is with dad, what do you need a "joint agreement" to do? Frankly the burden should be on the other side since, under the older cases, until and unless a stipulation is signed changing custody, he still owes you support notwithstanding where the child is physically.
I would not worry too much about "resulting in juvenile or something." If you did feel some need to go to court to formalize the current arrangement (your question does not indicate why you feel some pressure to do this) you could be quite general and indicate that the child's current attitude and behavior made you conclude that he would be better off living with his father for some time.
There may be missing facts that could make a difference. It might be in your best interest to schedule a consultation with this office, or your prior attorney, or some other, and have someone do a more detailed evaluation of the situation, and list your alternatives.
Answered on Jun 03rd, 2014 at 2:14 PM