Look at this case: Mum and Dad had a farm. Their son also had one, and he helped his parents with their one too.
Mum, Dad, and Son decided to form a Family Trust to hold all the assets used for servicing the farms. Mum, Dad and Son were all trustees and beneficiaries of the Trust.
Importantly, the son was made the ‘Appointor” of the Trust., which gave him the power to add trustees and to remove beneficiaries of the Trust. Presumably there was some reason for this at the time.
Sadly though, there was a falling out between the son and his parents. Son used his powers as appointor to remove Mum and Dad as beneficiaries of the Trust and to add a further two trustees. Ouch!