Make bank account name field mandatory when creating bank accounts for suppliers

Summary:

My client has asked us to make the "Account Name" field found under "Additional Information" mandatory when creating new bank accounts for suppliers. They have also asked that if bank account name field isn't populated, to prevent user from moving forward with process.

I have attempted to use the Sandbox to do this (as we are not using Redwood UI). Because when in the "Create Supplier" screens - the adding of a new bank account creates a "popup" page which is preventing me from using the sandbox to make the field mandatory.

Does anyone have any advice on how we can make this possible? Or if not possible, what workarounds have been proposed to satisfy what your client needs?