I have two questions

1) my interface i have interface called IRegister and within it i have another interface called IPerson, is that right practice?

2) i have two List(IRegister, IPerson) both can have one or more rows.

what is the best way to loop both List? within GetValidationRules?

public interface IRegister { string FirstName { get; } string MiddleName { get; } string LastName { get; } string EmailAddress { get; }
List Student { get; } }

public static List GetValidationRules(List register) { List validationRules = new List();

        foreach (IRegister myregister in register)
        {
            if (string.IsNullOrEmpty(myregister.FirstName))
                validationRules.Add(new ValidationRule("Reg", "Must have aFirst Name"));
            if (string.IsNullOrEmpty(myregister.LastName))
                validationRules.Add(new ValidationRule("Reg", "Must have a Last Name"));
            if (string.IsNullOrEmpty(myregister.EmailAddress))
                validationRules.Add(new ValidationRule("Reg", "Must have a Email Address"));

  IPerson here? how
        }