If you want to check the headcount for a specific branch within a certain time frame—i.e., how many employees accessed that branch, whether they belong to the parent branch or any other branch—follow these steps:
Go to Access Report → Footfall Report and select the Parent Branch in the filter criteria, you will only see users from that specific parent branch.
However, if you go to the filter criteria and select Advanced, you will be able to calculate the headcount for users from all branches who accessed that branch.
After that you can apply filter and select the particular branch.