Would the 300 days be in effect in this case?
from the Deleware Child Support Services page :
"Only the biological parents should sign the Acknowledgement of Paternity form. If you are not sure, do not sign the Acknowledgement. Instead, you should have a paternity test, sometimes called genetic testing. Please contact the nearest child support office for information about testing. If the mother was married during the 300 days before the birth of the child, OR if the mother was not married, but during the first two years from the birth of the child, another man continuously lived with the child and acknowledged the child as his own, then that man is considered to be the presumed father. In order for the mother and biological father to complete the Voluntary Acknowledgement, the mother and the presumed father must complete a form called the Denial of Paternity (DOP). Both the Denial of Paternity (DOP) and the Voluntary Acknowledgement of Paternity (VAP) must be filed with the Office of Vital Statistics (OVS). Neither document is valid until both have been filed. If a couple wishes to sign a VAP but are not sure who the biological father is, genetic testing should be obtained."