Can I transfer a balance from one customer to another?

Can I transfer a balance from one customer to another?

Issue: We are a member organisation and one customer (Member 1) has paid two annual membership fees. One for them and one for Member 2. Currently Member 1 has an overpayment recorded in the Unearned Revenue account while the Member 2's invoice shows as unpaid. I'd like to take the balance from Member 1 and transfer it to Member 2. 

Is this possible? Or will I need to 'split' the payment into two payments on the system. I have tried creating two payments at 50% of the amount each but that causes problems with the payment numbers.