You need to see a good solicitor, one that specialises in this sort of thing. I, too, have heard of the "sell it cheap" to a relative option and then let the one that inherited it live rent free for the duration. Bit more complicated than that i'm sure, that's why you need to see a solicitor.
This is not a situation for amateurs to advise you. The person concerned needs to consult a solicitor who is well versed in Inheritance Tax law. There are ways of setting properties in trust, but the law on this is changing all the time and your friend needs to consult an expert.