Expense Report submission without Bank Account

We have 2 Types of Expense Reports - One is submitted for Corporate Card Expenses and the other is for Employee Expense Reimbursement. The 2 types of reports are differentiated through a DFF created at Expense Report Header Level. The Bank Accounts have been made mandatory for both types of reports.

We have a requirement to make the Bank Account mandatory only for expense report which is of the Type - Employee Expense Reimbursement and to allow submission of report without Bank Account for expenses which are of the type Corporate Cards.

Kindly help me with a solution as to how can I achieve that?