My sister she sleep walks like all the time and she sometimes wake up on the sofa. Is there a way to stop her from sleep walking?

An important point to remember is not to wake them suddenly. Just steer them in the right direction and talk quietly and calmly to them.

Ensure that all your doors are locked at night so she doesn't walk outside.

If it's a continued thing, it's best to get the advice of a doctor to see what's possibly causing it. Perhaps stress, puberty (depending on the age), school pressures, boy pressures etc.