I am having some difficulty making fields on the Vendor Record mandatory. I have tried customizing the form and creating a workflow but cannot seem to get the field to be mandatory.

Under the subsidiary tab, how do I get the subsidiary and associated tax code to be mandatory?

Also when creating a bank details record, how can I make the subsidiary a mandatory field? I have tried creating a workflow, customising the form to make it mandatory and made the bank details subsidiary field itself mandatory, however nothing has worked.