In NY, if the father has a relationship with the child and signed the birth certificate, he's the father and will not be able to disclaim being the father of a five year old, even if the dna test came back negative. There is a Court of Appeals case directly on point.
If you'd like to discuss, please feel free to call.
Gold, Benes, LLP
1854 Bellmore Ave
Bellmore, NY 11710
Email - Jgold@goldbenes.com
The father can always request a DNA test, but once an acknowledgement of paternity is signed, then you cannot claim that the child is not yours. This should have been taken care of at the time the child was born.
If you signed an acknowledgment of paternity, your ability to set it aside after five years is very limited. Also, if you have a relationship with the child and the child thinks of you as the father, you will probably be prevented from going forward, and the court will not even order the DNA testing.
This anawer is not intended to create an attorney-client relationship and may be considered attorney advertising. This answer should not supplant advice received from any attorney the questioner may have or obtain, as that attorney will be able to provide more thorough and informed advice.