Holiday threshold by employee, rather than just number of people

Could the holiday threshold please be amended so that we can name the employees within a department who can’t be absent at the same time? Within a department, it’s not really good enough to simply say a certain number of staff can’t be off at the same time, if the ones who request holidays are all at the same level. Eg, it would be silly to let all supervisors/senior members of staff to be off at the same time, leaving apprentices in charge!

Thank you.