Run Autoinvoice program : Split credit memo into one invoice No.

In normal, I generated credit memo by SO#. The output is : one credit memo line equal to one SO line; These SO line may come from difference SO#. Each SO may have difference Invoice no..

The auto invoice program created a schedule job has setup by everyday of end. Thus, I received the credit memo with difference invoice no. at the next day.

My question is : I would like to split credit memo with same invoice no. for specify customer.  How can I split it without affect the other customer CMs?

Awaiting your reply. Thanks!!!