Cascading Validation on children validators

gistfile1.cs

public class OrderViewModel {
  public bool UsingOldCard {get;set;}
  public int OldCardId {get;set;}
  public NewCardViewModel NewCard {get;set}
  public int ItemId {get;set;}
}

public class NewCardViewModelValidator: AbstractValidator<NewCardViewModel> {
 public class NewCardViewModelValidator() {
    RuleFor(m => m.FirstName).NotEmpty();
    // etc.
 }
}

public class OrderViewModelValidator: AbstractValidator<OrderViewModel> {
  public OrderViewModelValidator() {
   RuleFor(m => NewCard).Unless(m => m.UsingOldCard); // doesn't exist (I don't think)
  }
}

// Also would be cool to see

public class OrderViewModelValidator: AbstractValidator<OrderViewModel> {
  public OrderViewModelValidator() {
   GroupRules(m => { 
        m.OldCardId.NotEmpty();
        m.ItemId.NotEmpty();
     }).Unless(m => ProductNotSoldOut(m.ItemId)); // doesn't exist (I don't think), different from RuleSets. I only want to execute all these rules if a condition is met.
  }
}

Like this?

RuleFor(x => x.NewCard).SetValidator(new NewCardViewModelValidator()).Unless(x => x.UsingOldCard)