Looks like your heifer has obturator paralysis-pressure from the calf inside her pelvis has compromised her obturator nerves.

Keep her well bedded, turn her so she's not laying on the same leg all the time. The sling to lift her is ok, but don't let her hang from it over 15 minutes at a time. Try to help her get her feet under her so she holds her weight herself. Massage of her leg muscles helps too.

If you can find a pair of "hip lifts" or "hip clamps" I prefer those over the under belly sling. Again 10-15 minutes at a time is enough to have lifted.

As stated earlier an anti-inflammatory such as dexamethasone or Banamine would be helpful.

If you've had her standing already, I'd bet you will win this battle.

Always drink upstream from the herd...cowdoc...