grandparent seeking custody

We adopted our daughter seven months ago. The adoption is not finalized because the paternal grandmother is seeking custody. After three and a half months in our care, the judge granted the adoption agency temporary managing conservator and gave the grandmother temporary possession. She now gets our daughter for one weekend a month. The judged told us to go to mediation. Nothing was accomplished. The grandmother is on her third husband, commonlaw, and they have no interest in getting to know us. They want the baby to be theirs and nothing else. They asked for holiday time and the judge granted them three separate visits in two weeks and an additional Sunday a month for four hours moving forward. We are schedule to go to trial on April 7th. In a nutshell .......birthfather abusive to mother and baby, child taken away a month after birth, birthfather killed two weeks later, his mother is granted TMC and the birthmother gets supervised visits, eight months later the grandmother sends two faxes and a voicemail to CPS saying baby belongs with other grandmother or foster home, three weeks later we meet birthmother and her mom, who is now PMC, to pursue adoption, a week later Lola is placed in our home, paternal grandmother finds out and she files for custody, she says if no one wanted the baby she would have kept her. We are depressed, frustrated, and scared we may lose our daughter. We are looking for any advice to help us keep our daughter and get through this nightmare.