Creating a list using data validation, can I create a subcategory list?

I have one column titled 'OpCo' (which means Operating Company) and the next column is 'Branch'. I need to base the data validation list in the 'branch' column based off of the 'OpCo' column.

I have 16 Operating Companies and each Operating Company has anywhere from 20 - 50 branches under it. I can create one list for all branches...but that is over 150 options. I would like to be able to only show the branches for the Operating company chosen.

See attached...

On tab 'PO & Invoice Details' it is columns E & F I need the lists for. I have no problem creating a list for column E. What I want is when a name is chosen for column E, then only to show options for that name chosen. See tab 'Branch City & ID' which shows eash OpCo and all branches per OpCo.

Is there a way with possibly to choose for instance 'Capital Tristate' for the OpCo column E on tab 'PO & Invoice Details' and then show ONLY Cooper Electric branches in column F from the tab titled 'Branch City & ID'?