Subform with mandatory fields being bypass by user and submitted

Subform with mandatory fields being bypass by user and submitted

Hello.  I am having an issue with Zoho Forms.  I have created a subform that has mandatory fields.  If the user decides to access this subform then they have to fill out those mandatory fields.  However if the user decides to not access the subform.  Those mandatory fields in the subform can go unfilled and the main form can be submitted.  


How do I make the subform a mandatory requirement that the user cannot bypass?