Journal entry to clear customer balances

We are transferring our Reckon file to a new entity, so need all customers to show zero balances. We don't want to set up a new entity as we want all the customers history to remain. I understand we should be able to do a Journal entry for this with A/R on one line to create a credit for each customer to then wipe their balance. What I'm trying to find out is what we put as the balancing transaction in the Journal - so if one line is A/R, what's the other line? Thanks in advance.