Ya ~ even in centre care when there was 'forehand knowledge' of a change in staff we always did our best to inform clients of it ~ it is not like you are 'asking permission' and they really have no 'say' in it cause it is your business and your choice and if having 'assistants' is a common part of your program than it should not come as a surprise to them to see a different face ~ informing them is just a common courtesy thing so that they are 'prepared' when they show up to a different face and so forth.