If I have a property whose display format is dependent on the value of another property in the view model how do I create a display template for it?

The combination of field1's display being dependent on field2's value will be used throughout the app and I would like to encapsulate this in a MVC 2 display template.

To be more specific, I've already create a display template (Social.ascx) for custom data type Social that masks a social security number for display. For instance, XXX-XX-1234.

[DataType("Social")]
public string SocialSecurityNumber { get; set; }

All employees also have an employeeID. Certain companies use the employee's social security number as either the whole employee id or as part of it. I need to also mask the employeeID if it contains the social. I'd like to create another display template (EmpID.ascx) to perform this task.

[DataType("EmpID")]
public string EmployeeID { get; set; }

The problem is that I don't know how to get both properties in the "EmpID" template to be able to perform the comparison.

Thanks for the help.