Field entry mandatory based on sales org

All,

We have a requirement where we need to make a field mandatory only for certain sales orgs on a sales order type.

I cannot add this field to the incompletion procedure assigned to the header level of this order type because it is used by multiple sales orgs and we only need to control it for orders created in one or two sales orgs. The field is a Z field in the additional data B tab available in the VBAK table.

Is there any standard way to achieve this or do we have to go for a custom development? Any ideas would be appreciated

Thanks,

Ravin