How to include bank holidays in the holiday allowance, then book these as a bulk booking for all the company
And then after creating the new leave you should check that the "Include in the allowance of" option for that event should specify your holiday type.(See the snapshot below).
Then create a new calendar which allows event of the new Company leave type. (See the snapshot below) and finally begin adding holidays to this new calendar. The newly added holidays will deduct from the holiday allowance.