Here's a scenario: A person owns 10 houses. He leaves 5 to his wife (4 investment, 1 PPOR), and gives the other 5 to nephews, nieces, one to charity, and his best friend for 40 years Jim. These are parties outside the immediate family where the default rules would apply (sons, daughters etc). Now to keep it simple imagine they are all worth exactly the same value. So basically, the wife gets 50%, the other 50% is given away. But is this person allowed to give 50%? Had they been divorced before he died, he wouldn't have necessarily been guaranteed 50%, so how could he assume that he is allowed to do what he wants with "his" 50% when he dies? What I'm basically asking is, when divorcing, the determination of the asset split can be subject to so many factors. Therefore isn't dying subject to those same complexities? If so, how could anyone possibly plan a rock solid Will without lots of these problems cropping up? Or is dying a lot simpler, whereby there is a fixed percentage already designated by law that each person is allowed to allocate to whomever they want (i.e. 50/50)?