Hi Venu,
Further to Waza's detailed explanation, you can try in the below way aslo,
Have different risk category for the customers who you don't want to do the credit check and assign the routine in OVA8, so that system will by pass them as per your requirment.
But, Any Idea business wants to ignore few customers who are already under credit management? Its good to know the business reason.
Regards, Sai Krishna.