So forced mods can either be assigned to a regular menu item by also can be assigned to a modifier itself.   

An example of a forced mod on a mod would be a side choice.   Then if they pick salad there would be a forced mod for dressing choice on the salad. 

It is possible to create a circular reference.  By this you can create forced mods that circle back on themselves.   Basically creating an issue where forced mods never go away and user is forced to restart computer to exit.   Make sure to test all forced mods for desired functionality.  

Further tips:    Always create an out on a forced mod.  If it's a side choice create an option for no side.  If it's something that can't be defined allow for special instructions as an option. Also, in the case where it's a pick 2 or 3, allow for the option that someone may pick 2 or 3 of the same  item.