How to advocate for and get the best for a child?

Please tell me what to do. We have an absolutely wonderful little 5 yr old girl in our home. This is our first foster placement and we went into this hoping to adopt. It was an emergency placement that has become longterm indefinite. Mom is in jail for drugs, dad is in & out of jail for drugs and has shamefully abused this little girl. CYS talked to her and she told them about him badtouching her. Next step is that she is to talk to a plainclothes officer about the abuse so that charges can be filed. This was about 2 months ago. No officer has come yet, I'm told it's still supposed to be happening. We have biweekly visits w/ an older family member who is unable to care for her, but does love her and is probably one of few who's ever come close to doing right by this child. Mom is hoping to get out of jail, get clean and get her back. This is not bmom's first time in jail. I'm assuming that that is the "plan" until the mother shows otherwise. We love this child, she has called us mommy & daddy from day one and wants a family so bad. She gets so excited when teh 3 of us do anything together because she has a mommy & a daddy and we're a family. She tells us she wants to live w/ us forever and has not wanted anything to do w/ her bmom since before us. Since day one she has said she wants to never move again, stay here. she tells us "i love you" constantly. She previously stayed w/ an aunt, several other family members and grama and was in teh foster system before this at some point that I don't know. There is no other family member able or suitable to keep her. while I painfully realize that she could be removed from our home at some point, I don't want to look back in retrospect and wish I had known that I should've done this or that. So far I'm documenting all abuse that she's telling me about and I'm careful not to lead and I'm documenting it in the proper form and forwarding it all to CYS. We recently got a different social worker, the first one was for short term placements and we've gotten another that's one for longterm. So far, I haven't had that much interaction with her to see what she's like, if she cares or whatever. I did get the name of our fd's GAL atty and want to contact him to ask what I could be doing. Also, I want to get her into some therapy w/ a therapist since I've found that a therapist can be called as an eyewitness for abuse that she would talk about. I think that the mother was also abusive, but that hasn't come out yet. I would say certainly neglectful. What things do I need to do on behalf of this child so that if/when things go to court I've done what I should for her best interest and if we have a chance to keep her that I have the proper documentation and actions in place?