How do I send the form datas 2 classes?

Question

hi my friend my english is not good.. I hope you can understand me.
I have a form but I want to send data to 2 class thank you..


public class ContractItem
{

 public string Name { get; set; } 

 public string LastName { get; set;} 

}

---

public class PaymentItem

{

public int PaymentSalary { get; set; }

public date SalaryDate { get; set; }

}

---

example html

Form <form name="Ajaxform" method="POST">

Name : mike Last Name : anderson

Salary : 100 $  Date : 10/01/2014

</form>

---

function AjaxForm(form, action)

{
temp = $("form").serializeArray();

var SendData = {};

AddContract(SendData);

}

---

function AddContract(data)

{ //( data = mike,anderson,100,10/01/2014 ( 4 data comes successfully )
var status = false;
$.ajax(

{ url: 'Contract/AddContract',
type: "POST",
data: JSON.stringify({ item: data }),
contentType: 'application/json; charset=utf-8',
dataType: 'json',
async: false,
success: function (Id)

{

},
error: function (jqXHR, textStatus, errorThrown) {

}

});

}

---

HttpPost] public JsonResult AddContract(ContractItem)

{
bool Status = false;

return Json(Status, JsonRequestBehavior.AllowGet);

}

---

public JsonResult AddContract(ContractItem) (If I use this code ,only mike,anderson data comes successfully )

public JsonResult AddContract(PaymentItem) (and If I use this code, only 100,10/01/2014 data comes successfully )

How do I merge data? or How do I make dynamic inheritance?

example
ContractItem : PaymentItem
I tried to use a tuple, but it did not work
public JsonResult AddContract(Tuple<ContractItem,PaymentItem> item)