Bill To address change on a Customer who has Open Balances

Hi there,

We are using BFB for a long time, which is at Customer Account.

Question is:

Say there is an established Customer who has different Statuses on the Account Details form (for example, Credit Memos which have Status : Closed, and Invoices both with Status: Closed and OPEN).  After the last Billing Cycle, Customer sends us a notice saying his Bill To address needs to be changed. 

How would BFB calculate the Current Balance and Ending Balance on the next Billing Cycle? Will it use 2 different Bill To sites? Would it merge the OPen Balances on the NEW Bill To Site?