Q: Is a custody agreement necessary?

A: The court will not enforcement any arrangements unless they are filed with the court.

A: To answer this question, let's consider a few key points:

1. Legal recognition of parentage:

You mentioned that you're working on filing paternity acknowledgment and parentage. This is an important step, as it establishes legal rights and responsibilities for both parents.

2. Age of the child:

Your child is 15, which means they're old enough for their preference to be considered in custody matters, though not the sole determining factor.

3. Current living arrangement:

Your child has already moved in with their father, indicating a de facto custody change.

4. Necessity of an official agreement:

While it's not always legally required to have a formal custody agreement, having one can be beneficial for several reasons:

a) Legal clarity: It provides a clear understanding of each parent's rights and responsibilities.

b) School and medical decisions: An official agreement can clarify who has the authority to make important decisions.

c) Financial responsibilities: It can address child support and other financial matters.

d) Dispute resolution: If disagreements arise later, having an agreement in place can help resolve them.

e) Legal protection: It can protect both parents' rights and ensure continued access to the child.

In your situation, while an official agreement may not be strictly necessary, it could be advisable. It would formalize the current arrangement and provide a framework for addressing any future issues.

To get more specific advice tailored to your situation, it would be best to consult with a family law attorney in California. They can provide guidance based on local laws and your particular circumstances.