objdsInvoice.Relations("put_your_relation_name").ChildTable

Imports System.Data
Public Class Form1
    'Dataset
    Dim ds As New DataSet("MyDb")
    Dim bindStu As BindingSource
    Dim bindMks As BindingSource
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim dt1 As New DataTable("Student")
 
        dt1.Columns.Add("Roll", GetType(Integer))
        dt1.Columns.Add("Name")
 
        'Primary key
        dt1.PrimaryKey = New DataColumn() {dt1.Columns(0)}
 
        dt1.Rows.Add(1, "A")
        dt1.Rows.Add(2, "B")
 
        'Second table - Marks
        Dim dt2 As New DataTable("Marks")
        dt2.Columns.Add("Roll", GetType(Integer))
        dt2.Columns.Add("Subject")
        dt2.Columns.Add("MarksObt", GetType(Integer))
 
        dt2.Rows.Add(1, "Sub1", 50)
        dt2.Rows.Add(1, "Sub2", 80)
        dt2.Rows.Add(2, "Sub1", 87)
        dt2.Rows.Add(2, "Sub2", 77)
        dt2.Rows.Add(2, "Sub3", 98)
 
 
        ds.Tables.Add(dt1)
        ds.Tables.Add(dt2)
 
        'Create parent-child relationship
        Dim rel1 As New DataRelation("rel1", dt1.Columns(0), dt2.Columns(0))
        ds.Relations.Add(rel1)
 
        'Create binding source for parent table
        bindStu = New BindingSource(ds, "Student")
 
        'Create binding source for child table
        bindMks = New BindingSource(bindStu, "rel1")
 
 
        TextBox1.DataBindings.Add("Text", bindStu, "Roll")
        TextBox2.DataBindings.Add("Text", bindStu, "Name")
 
        DataGridView1.DataSource = bindMks
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        bindStu.Position += 1
    End Sub
End Class

<Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _
Partial Class Form1
    Inherits System.Windows.Forms.Form
 
    'Form overrides dispose to clean up the component list.
    <System.Diagnostics.DebuggerNonUserCode()> _
    Protected Overrides Sub Dispose(ByVal disposing As Boolean)
        Try
            If disposing AndAlso components IsNot Nothing Then
                components.Dispose()
            End If
        Finally
            MyBase.Dispose(disposing)
        End Try
    End Sub
 
    'Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer
 
    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.  
    'Do not modify it using the code editor.
    <System.Diagnostics.DebuggerStepThrough()> _
    Private Sub InitializeComponent()
        Me.TextBox1 = New System.Windows.Forms.TextBox
        Me.TextBox2 = New System.Windows.Forms.TextBox
        Me.DataGridView1 = New System.Windows.Forms.DataGridView
        Me.Button1 = New System.Windows.Forms.Button
        CType(Me.DataGridView1, System.ComponentModel.ISupportInitialize).BeginInit()
        Me.SuspendLayout()
        '
        'TextBox1
        '
        Me.TextBox1.Location = New System.Drawing.Point(164, 38)
        Me.TextBox1.Name = "TextBox1"
        Me.TextBox1.Size = New System.Drawing.Size(100, 20)
        Me.TextBox1.TabIndex = 0
        '
        'TextBox2
        '
        Me.TextBox2.Location = New System.Drawing.Point(164, 64)
        Me.TextBox2.Name = "TextBox2"
        Me.TextBox2.Size = New System.Drawing.Size(100, 20)
        Me.TextBox2.TabIndex = 0
        '
        'DataGridView1
        '
        Me.DataGridView1.ColumnHeadersHeightSizeMode = System.Windows.Forms.DataGridViewColumnHeadersHeightSizeMode.AutoSize
        Me.DataGridView1.Location = New System.Drawing.Point(89, 144)
        Me.DataGridView1.Name = "DataGridView1"
        Me.DataGridView1.Size = New System.Drawing.Size(240, 150)
        Me.DataGridView1.TabIndex = 1
        '
        'Button1
        '
        Me.Button1.Location = New System.Drawing.Point(164, 103)
        Me.Button1.Name = "Button1"
        Me.Button1.Size = New System.Drawing.Size(75, 23)
        Me.Button1.TabIndex = 2
        Me.Button1.Text = "Button1"
        Me.Button1.UseVisualStyleBackColor = True
        '
        'Form1
        '
        Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
        Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
        Me.ClientSize = New System.Drawing.Size(461, 320)
        Me.Controls.Add(Me.Button1)
        Me.Controls.Add(Me.DataGridView1)
        Me.Controls.Add(Me.TextBox2)
        Me.Controls.Add(Me.TextBox1)
        Me.Name = "Form1"
        Me.Text = "Form1"
        CType(Me.DataGridView1, System.ComponentModel.ISupportInitialize).EndInit()
        Me.ResumeLayout(False)
        Me.PerformLayout()
 
    End Sub
    Friend WithEvents TextBox1 As System.Windows.Forms.TextBox
    Friend WithEvents TextBox2 As System.Windows.Forms.TextBox
    Friend WithEvents DataGridView1 As System.Windows.Forms.DataGridView
    Friend WithEvents Button1 As System.Windows.Forms.Button
 
End Class