More information is needed to accurately respond.
You should consult an attorney for advice regarding your individual situation since every case is different and not all information is relayed in an online question. The Law Office of Ophelia Bernal-Mora, P.A. is a family & criminal law firm located in Orlando, Florida, we invite you to contact us and welcome your calls at 407-377-6828. Contacting us does not create an attorney-client relationship. Please do not send any confidential information to us until such time as an attorney-client relationship has been established.
I don't understand your question. I don't even understand if the person you want child support from is the legal or biological father. We're you married to him when your child was born? You'll have to explain better before I can give you an answer.
The contents of this answer should be considered friendly advice, not legal advice (I'm a pretty friendly guy), and the answer should not be construed to constitute an attorney-client relationship. If you'd like actual legal advice, call me for a free consultation at 813-635-0222. Also, if you liked this answer as much as my big ego thinks you did, be sure to click the thumbs-up button!
I do not fully understand the question either. You cannot get child support from a step father unless the child was adopted by him. Where in the US are you going to move. You cannot just annul an agreement, where was the agreement entered into and did the court incorporate it into a final judgment? Far too many unanswered questions to make a stab at yours.
Child support is awarded by FL courts based upon the financial circumstances of both biological or adoptive parents. FL does not recognize virtual adoptions. If your ex husband is not the biological parent of your child its not likely that you will be able to get a court to award support for your son from him despite the close relationship they created. You may want to hire someone who investigate the assets of the child's biological father.
FOR ANYONE READING THIS BLOG OR QUESTION POSERS ON AVVO:
The response to questions posted on facebook which are responses to questions submitted by anonymous persons on AVVO are in no way intended to establish any form of attorney-client relationship with either the anonymous AVVO question submitters or any facebook readers nor should they rely on this information in any pending legal matter. The responses given are deemed as responses to general questions and fact scenarios posed as an educational exercise only, should in no way be deemed legal advice provided to any persons in states in which the author is not licensed to practice law or viewed as a solicitation of clients from those states in which the author is not duly licensed to practice law, should not been deemed as psychological counseling advice or psychological advice for which this author is in no way qualified to provide nor should any reader rely on any such information without first seeking advice from an attorney at law, licensed in the state of the reader’s residence in regard to any information posted or from a licensed qualified psychiatrist, psychologist, mental health employee, licensed clinical social worker, marriage counselor or other persons licensed by their respective state to provide mental health advice. To the best of the author’s knowledge the questions may well be generated for pedagogical purposes only and not necessarily posted from real persons seeking legal advice.