SB will be in her element in prison. She's a baby-beater with no limits, and a big strong fit woman who will quickly have people frightened of her and a lot of slaves, girlfriends, and hangers-on. As someone else listed, she'll have food, medical care, gym, and TV. It doesn't seem like enough of a 'price' to pay for that poor little girl's months'-long suffering and death.
I'm not sure about FS and obviously the judge/jury didn't quite know what to make of her, either? Did she crack that tiny baby's head against a wall and twist her leg till it broke? Was she SO stupid she didn't even NOTICE a fracture or did she know who did it and didn't want to get SB into trouble? But the thought of her on her phone while the baby tried slowly and painfully to climb the stairs, plus dragging her round the shops that time, plus all those other little cruelties we heard about, to my mind mean she deserved a lot longer sentence than she got.