18 Year Old /15 Year Old

My question involves criminal law for the state CT
When my daughter was 18, she met a boy who told her he was 19. They started dating, and she beccame pregant.He even moved in with us for a while. When they broke up, she found out he was 15 at the time she became pregant. Turned 16 when she was 1 month along. He just now turned 17 and my daughter will be 20 in 2 months. My daughter is taking him to court for sole custody of the baby(who is 4 months). Someone told her that if his mother wants she can still press charges against my daughter now. The mother was aware of my daughters age the whole time, and she is the one who told my daughter his true age when they broke up. Is this true, can they file charges against my daughter?

They can certainly file a police report. Whether charges would be brought or not will be up to the DA, but CT law is very clear that any person under the age of 16 is going to be considered to be unable to give consent (ie no "Romeo and Juliett" application) and the state can pursue sexual activity with such 15 year old as a felony.

Your daughter is in trouble. She's two years older and it's "Second-degree sexual assault to have sexual intercourse with a person between ages 13 and 16 if the actor is more than two years older" She faces up to 20 years in prison (nine months mandatory minimum).