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I am sorry to hear about this situation, S. Understand that you as a non-parent have no legal standing to initiate any court procedure for custody. Only a parent or a times a relative or a person who has had informal custody for some time can do so, as well as CPS.
There are two things that can be done here:
1) If Mr. Brown files for modification of custody via the court, you can testify as an expert for MR. Brown. The Court determines custody based on "best interest of the child," meaning general stability of the parent, financial stability, indoctrination of the child in the current school and environment, household condition and living condition of the child, other persons living in the house, etc.
2) If Mr. Brown or another third party was to call in an anonymous CPS complaint and CPS was to investigate, then someone in your situation may be contacted to provide their opinion on the matter. CPS normally wants to place a child with other family if possible, so CPS may then place the child with Mr. Brown. As in #1, formal testimony from you may be required.
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