If you're managing several SIM cards in your account, you'll receive one invoice/payment invitation per SIM card with a subscription, and one invoice/payment invitation that includes all of your prepaid SIM cards.
However, all these payment documents use the same details. Would you like to use different details, for instance to receive invoices with your company details for a particular SIM card? In that case, you'll have to sign up for a separate Mobile Vikings account. You can do so by logging out of your current account when requesting that particular SIM card.
Would you like to update details for an already active SIM card? No problem at all. Create a new account first. Then, in the original account, you can transfer the SIM card to the new account via "My products" --> "SIM authorizations".