How to make field mandatory in Order Management using Form Personalisation

Making flex field segments mandatory can be difficult via personalizations because of how the forms handle them.  It may be easier to do it using the flex field validation instead.  Make attributes 9 and 10 mandatory on the flex field definition, then set a default value that populates only when the customer is *not* XYZ.   For example, the default value for the segments could be something like    select 'N/A' from dual where customer <> XYZ.    When you enter an order for customer XYZ the default is blank and the user is forced to enter a value.  When you enter an order for other customers, the value defaults to N/A and the user doesn't have to touch the segments unless he wants to change from NA to something else.