Have charges been filed against the mother's boyfriend and/or the mother? And has CPS or the local Children's Advocacy Center (CAC) conducted a forensic interview with your step-daughter yet? I am not sure how it works where you live (or where the abuse took place), but in my area (Dallas/Fort Worth), when an outcry of sexual abuse is made and reported to CPS, the child is typically videotaped at the CAC in a forensic interview. And the CAC has all kinds of therapeutic services that are offered to the child. I would also make a report to CPS based on your current concerns - given that there is a history of abuse/neglect, you might have a better chance of getting them involved again.