According to Michael Logan from TV Insider, Martinez debuts in the role on March 1, and will be interacting with Nick (Joshua Morrow) and Sage (Kelly Sullivan). Shawn is a young pregnant woman looking for the perfect parents to adopt her child.
When the casting call for Shawn first went out, she was described as being pretty, yet extremely practical. I hope she uses good judgement if she is considering letting Nick and Sage adopt her child!
You can read Michael Logan's full interview with Martinez here.