Help Needed!!

I'm in the middle of a very heart breaking situation so I am very sorry about the novel of a post I am about to make. My husband and I adopted a sibling set of 3 almost 3 years ago now. In September we found out that our oldest daughter had been sexually abusing our youngest daughter as well as other young extended family members. She bounced around between our mothers' houses for several months and then in November CPS sent her back home and tried to close out the case because no criminal charges were files since she was only 11. She was only home for a few days before going back to being defiant and disrespectful and stating that she would "hurt" my younger daughter again. She tried to get her alone numerous times and tried to sneak into her room at night despite the security cameras we installed and the alarm we had put on her door. We reported all of this back to CPS and told them we couldn't have her living in our house anymore. At that point we just wanted CPS to help us get her into some kind of treatment program. CPS took Temporary Managing Conservatorship of her and filed a Refusal to Accept Parental Responsibilities case against us that was eventually ruled out because we did everything we could to get her help before going back to CPS. We still have parental rights and are able to talk and visit with her. In Texas there are no programs for adolescent females who are sex offenders so they just placed her in a regular RTC. It didn't take her long to figure out all she had to do was behave for 3 months and she could get out of the RTC. She is currently in a foster home with three older girls and has already stolen money, been disrespectful towards the foster mom, and been physically aggressive towards the girls in the house and girls at a summer camp she attended. As of now CPS still has the goal set as reunification although it is very unlikely that will occur and we are not willing to let her come back home as long as she is a safety risk for our two younger children. The trial date is set for October and it looks like CPS will be taking Permanent Managing Conservatorship at that point because she has not made enough progress to safely return home. She has RAD, ADHD, PTSD, and possible mood disorder. At the time of placement we only knew of the ADHD, and although the sexual abuse of my younger daughter had begun in foster care nobody was aware of it because it had been going on for so long my younger daughter thought it was normal. She was in weekly therapy, and visited many psychiatrists since the day we brought her home. She never formed a bond with us and never showed any kind of affection towards our younger two children. She was very hateful towards them and constantly trying to hurt them or get them in trouble. I am a behavior teacher at a local elementary and work closely with a small group of third and fourth graders who have severe behavior problems. Very soon after we discovered everything and made the CPS report I found out that one of my students who was in CPS custody but living with an aunt in the area would soon be moved with his siblings back into foster care in the Fort Worth area as the aunt was no longer able to care for them. I spoke with their caseworker several times but because their was an active investigation at the time he said placement with us wasn't possible. In March the case worker called me again to see if we were still interested in taking placement of the siblings because their previous placements had fallen through. I said we were still interested and gave him an update on our case letting him know that our daughter was now in TMC in CPS. He said he would have to get supervisor approval and would get back to me but I haven't heard from him since and he doesn't respond back to any form of communication from me. I was able to talk to the CASA worker for the sibling group and she told me they decided placement with us was not possible but did not give me a reason for the decision. Would it ever be possible for us to get placement with our daughter in TMC/PMC of CPS? My former student is a special needs kiddo with ADHD/Autism and Speech/OT delays. He has been in a residential home since November because they could not find family members will to take him. My heart breaks for him everyday and if there is anything I could possibly do for him I would. I just don't know where to go from here.