I take the view that if the facts of the question state that a property owner has made a declaration; then you can accept that statement at face value.
I accept that there would be practicalities of proof in 'the real world' but, unless it's an exam on the law of evidence, then the facts stated in an exam don't have to be 'proved' at the academic stage of study. It's the same for tort, crime, land etc.
The OP suggests that the student is confused about what happens when a property owner trustee dies following an attempt to declare an inter vivos trust. They key issue in relation to the stated facts is the potential problem with regard to the subject matter. That's what I would concentrate on (unless, of course, Sharon has more than one un-named sister!).