If she is under 18, they can prevent her from seeing your son, and control her in many other ways. However, they cannot keep her from getting proper medical care, or it should be reported to Social Services. Whether it is definitely child abuse is up to the authorities.
Hopefully, these young people will soon be able to make their plans without any further interference. These people will be so sorry if they are ruining their chances with their future grandchild.
Your son cannot sign a Declaration of Paternity until after the child is born. Forms will be available at the hospital. Here are some FAQ's which provide a lot of information:
DISCLAIMER: Answers from Experts on JustAnswer are not substitutes for the advice of an attorney. JustAnswer is a public forum and questions and responses are not private or confidential or protected by the attorney-client privilege. The Expert above is not your attorney, and the response above is not legal advice. You should not read this response to propose specific action or address specific circumstances, but only to give you a sense of general principles of law that might affect the situation you describe. Application of these general principles to particular circumstances must be done by a lawyer who has spoken with you in confidence, learned all relevant information, and explored various options. Before acting on these general principles, you should hire a lawyer licensed to practice law in the jurisdiction to which your question pertains.
The responses above are from individual Experts, not JustAnswer. The site and services are provided “as is”. To view the verified credential of an Expert, click on the “Verified” symbol in the Expert’s profile. This site is not for emergency questions which should be directed immediately by telephone or in-person to qualified professionals. Please carefully read the Terms of Service (last updated February 8, 2012).