Validation of customer in Custom table in Event Management System

Hi Experts,

I have a requirement where i need to maintain the decision table in Event Management system with the fields of sold to party, ship to party , incoterm1 & route.But there is no check table KNA1 for validating customer field value. So, how can we validate sold to party/ship to party entries when there is no check table.

Appreciate your inputs.

Thanks and Regards

Nethra