Custom Fields on Credit Card Expense Submissions Through Expense Management

Hello,

We are in the process of setting up and I recently noticed that from within expense management it doesn't seem to allow you to attach a custom fields when you are submitting a credit card expense. But when submitting an invoice there is the option to attached the custom field. This seems odd to me since they are so similar. Does anyone know if that is correct or if there is a work around to get a custom field attached to a credit card expense?