in evaluating situations like this:
go to [www.deikman.com,
] go to the section on cults and read 'Evaluating Spiritual and Utopian Groups.'
It is commonplace for untrained healers to argue that the functioning ego is a trap. The thing is, the functioning ego is like our skeletons. We need it in order to function on a day to day basis. Genuine spiritual growth preserves the integrity of your ego, but shows you that there's reality far beyond your ego. You retain your sense of ethics, your boundaries and your ability to function responsibly.
I hope your sister gets help in reconsolidating her personality.