Unique names list from data validation column

Hi there,

I'm trying to find a formula to create a list of names not yet used in a column that has data validation. I've attached a sample file of what I am trying to achieve with two examples.

The yellow highlighted list at the bottom of column I is what I am trying to create and is the list of names not yet used in the schedule above it (Range I3:I22).
Column F is the list of names used for validation in column I and is made up of columns B (Staff) and D (Management).

For the purpose of the schedule I only need to know which members of staff from column B have not been used on the schedule (yellow highlighted list at the bottom of column I). I have seen reducing validation lists that cut names out of the validation list as they are used but this will not work as I need to use names more than once on the schedule. I have tried to adapt some of these ideas but have spent hours getting nowhere.

Any help in getting a formula or set of formulas to do this would be appreciated.

Thanks in advance,