just try and get them to land on 2 feet.  also check their posture on landing, and make sure their chest is up, and not dropped as this causes them to have their forward momentum well in front of their feet and increases the likelihood of stepping.  so have them running to you, hop or jump onto the pass landing with 2 feet, pivot and pass to the next person.  also check that they are landing with bent knees to help with balance.  hope that helps.