Bub is posterior though, but Spinning Babies was suggested in an attempt to turn bub before birth.

He also told her that she had a greater risk of rupturing her uterus, and hemorrhaging from forceps use to turn bub, and that it could result in a full hysterectomy.
You can birth a bub that is posterior (my LO came out this way), it's not as comfy but doesn't require forceps to turn bub. Also, bub can turn during labour if they haven't turned before.

Does your sister have a midwife she can chat to?