Two Way Data Binding of Combo Box VB.Net - vb.net

Question

I am trying to get the two-way combo box binding work. I have a class which serves as source for combo box and i bind the selected item/value of the combo box to data table and the data table is bound to data grid view with binding source. It works but not as i expect it to be. I want to achieve two things.
Update the Data table Grid view as soon as selection changes in the combo box (force update of data)
Add binding to Age column
Here is my code. What is the right way to do. Any help would be highly appreciated. Thanks
Imports System.ComponentModel
Imports System.Runtime.CompilerServices
Public Class Form1
Implements INotifyPropertyChanged
Public BS As New BindingSource
Public ContactBL As BindingList(Of Contacts)
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim contacts As New List(Of Contacts) From {
New Contacts() With {.FirstName = "Name1", .LastName = "LName1", .Age = 50},
New Contacts() With {.FirstName = "Name2", .LastName = "LName2", .Age = 39},
New Contacts() With {.FirstName = "Name3", .LastName = "LName3", .Age = 30},
New Contacts() With {.FirstName = "Name4", .LastName = "LName4", .Age = 66}}
ContactBL = New BindingList(Of Contacts)(contacts)
ComboBox1.DataSource = ContactBL
ComboBox1.DisplayMember = "FirstName"
ComboBox1.ValueMember = "LastName"
Dim table As New DataTable("Tab1")
table.Columns.Add("FirstName", GetType(String))
table.Columns.Add("LastName", GetType(String))
table.Columns.Add("Age", GetType(Integer))
table.Rows.Add("Name3", "LName3", 30)
table.Rows.Add("Name2", "LName2", 39)
BS.DataSource = table
DataGridView1.DataSource = BS
ComboBox1.DataBindings.Add("SelectedValue", BS, "LastName", True, DataSourceUpdateMode.OnPropertyChanged)
ComboBox1.DataBindings.Add("Text", BS, "FirstName", True, DataSourceUpdateMode.OnPropertyChanged)
DataGridView2.DataSource = ContactBL
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim nr = CType(ComboBox1.SelectedItem, Contacts)
Dim NewRow = DirectCast(BS.AddNew(), DataRowView)
NewRow("FirstName") = nr.FirstName
NewRow("LastName") = nr.LastName
NewRow("Age") = nr.Age
BS.EndEdit()
End Sub
Private _FirstName As String
Public Property FirstName() As String
Get
Return _FirstName
End Get
Set(ByVal value As String)
_FirstName = value
OnPropertyChanged()
End Set
End Property
Private _LastName As String
Public Property LastName() As String
Get
Return _LastName
End Get
Set(ByVal value As String)
_LastName = value
OnPropertyChanged()
End Set
End Property
Private _Age As Integer
Public Property Age() As Integer
Get
Return _Age
End Get
Set(ByVal value As Integer)
_Age = value
OnPropertyChanged()
End Set
End Property
Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged
Protected Overridable Sub OnPropertyChanged(<CallerMemberName>
Optional memberName As String = Nothing)
RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(memberName))
End Sub
Sub BindingComplete(ByVal sender As Object, ByVal e As BindingCompleteEventArgs)
If e.BindingCompleteContext = BindingCompleteContext.DataSourceUpdate AndAlso e.Exception Is Nothing Then e.Binding.BindingManagerBase.EndCurrentEdit()
End Sub
End Class
Public Class Contacts
Implements INotifyPropertyChanged
Private _firstName As String
Private _lastName As String
Private _Age As Integer
Public Property ContactId() As Integer
Public Property FirstName() As String
Get
Return _firstName
End Get
Set
_firstName = Value
OnPropertyChanged()
End Set
End Property
Public Property LastName() As String
Get
Return _lastName
End Get
Set
_lastName = Value
OnPropertyChanged()
End Set
End Property
Public Property Age() As Integer
Get
Return _Age
End Get
Set
_Age = Value
OnPropertyChanged()
End Set
End Property
Public ReadOnly Property FullName() As String
Get
Return $"{FirstName} {LastName}"
End Get
End Property
Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged
Protected Overridable Sub OnPropertyChanged(<CallerMemberName>
Optional memberName As String = Nothing)
RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(memberName))
End Sub
End Class
Thanks