Legal question. Can they do this?

My husband had a daughter before me and I have gotten to know her since she was 2 years old. She has been living in Missouri this whole time after there split when she was 1. We used to get her every 2 months, and sometimes for 6 months straight. Well of course it all changed when she turned 5 and school started. Since she lives 8hrs away she gave us Christmas and summer. Bummer right! Well it really hit us hard when we had to give her back yesterday. We got told when we get her for summer they are moving her to FLORIDA! A 16 Hour trip 1 way! And she does not meet us half way. Ever. We will call he M. M cried to us saying she doesn't want to move and that she doesn't want to go home. That she wanted us. But when we asked if she was serious she said she would have to do 'minie miney mo' so that told us she's still way to young even though she claims she wants to stay with us. We have been keeping a mommy diary I guess if you call it. Her mom gave her scabies when she was 2 from not washing her and now She was caught taking pictures of her and her cousins no no spots. Which we asked her mom to put her in counseling. But she hasn't. We all have been messed with so it worried us. Is there anything we can do legally? We don't want to take her away from her mommy because every girl needs her mommy. But 16hrs one way is crazy. We don't live off our parents like she does so we don't have that kind of money to go and get her since she won't meet us. We will then be classified as 'bad' people. My husband may work full time but he gets paid under minimum wage and I work but at the end of the day bills+that drive won't work. I know this may sound like we're bad parents but she means the world to us. If we can't do anything legal wise what are ways we can still be there for her? She wants no one but her daddy right now and she has expressed how this move will hurt her because she wants her daddy. Her mom's gf cheated on her so they think moving to where she is from will help. Why not move closer to us so she can see her daddy every weekend if she wants? I'm at a loss of what to think to do. We don't want to drag a 6yr old threw court but we don't want her to think that we don't fight for her. She's my husband's only kid and he suffers from so much depression. Her mom will even give more time to his aunt and they not tell us she's here for 4 weeks already and her be 30min down the road. That happened last summer. Ik I'm rambling and will probably get alot of hate for this because she's 'not my child' but I've been here for 4 going on 5yrs and I've watched her grow and she was there for me when I was losing her sibling to miscarriage. And to find out she's all I will ever see grow up.

We already call and video chat every day. I just don't want her to think she isn't important to us since there taking her so dang far away