On enter key press in TextBox on childform , reply from ProcessCMDKey of MDIParent

I have some simple program code on Main form (which is MDIParent) to capture the Keys and running some Methods.

I have another form (which is MDIchild) in this Program in which I am using TextBox_Keydown event to show/Hide one DGV(on Panel).
I want that On Pressing Enter Key, Value selected in DGV must be Copied to Textbox, but actually on Pressing Enter Key “ProcessDialogKey” Function, which is written in MainForm Logic is running.
I am not able to understand why this is happening, May someone help?

Code:

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''Code in MDIParent MainForm is as under
Protected Overrides Function ProcessCmdKey(ByVal keyData As System.Windows.Forms.Keys) As Boolean

            Select Case keyData
            Case Keys.Enter
                ‘ Some logic here
                MastripMenuItem.ShowDropDown()
                Return True

            Case Keys.Escape
                EXITToolStripMenuItem1.PerformClick()
                Return True

            Case (Keys.Left + Keys.Shift)
                DTroutine() ‘ Some Method for Database Modification
                Return True

            Case Else
                Return MyBase.ProcessDialogKey(keyData)
        End Select
       
        Return MyBase.ProcessDialogKey(keyData)
    End Function

'Code in MDIChild Form is as under

Private Sub TxtParty_KeyDown(sender As Object, e As KeyEventArgs) Handles TxtParty.KeyDown
      If DGVPartySearch.RowCount = 0 Then e.Handled = False : Exit Sub
 
        If PanelDGV.Visible = True Then
         
            '                nRowDGParty is rowindex on DGVPartySearch
            DGVPartySearch.ClearSelection()
            DGVPartySearch.Rows(nRowDGParty).Selected = True
            TxtParty.Focus()
      End If
 
          If e.KeyData = Keys.Down Then
          If PanelDGV.Visible = False Then
                PanelDGV.Visible = True
             
                e.Handled = e.SuppressKeyPress = True
              Exit Sub
            Else
                If nRowDGParty + 1 < DGVPartySearch.RowCount Then
                    DGVPartySearch.ClearSelection()
                    nRowDGParty += 1
                    DGVPartySearch.Rows(nRowDGParty).Selected = True
                    TxtParty.Focus()
                End If
                'e.Handled = True
                e.Handled = e.SuppressKeyPress = True
            End If
            Exit Sub
        End If
       
        If e.KeyData = Keys.Enter OrElse e.KeyData = Keys.Return Then
          If PanelDGV.Visible = True Then
                Dim AccName As String = DGVPartySearch.Item(0, nRowDGParty).Value
                          TxtParty.Text = AccName
                          TxtParty.Select(TxtParty.Text.Length, 0)
 
                PanelDGV.Hide()
                e.Handled = e.SuppressKeyPress = True
                Exit Sub
            End If
        End If
        e.Handled = False
    End Sub

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In an MDI application, the child form is part of the parent. The parent has an MdiClient control added to it - that's why the form changes to a grey colour - and the child forms are then added to that as controls. That ProcessCmdKey method is invoked just as it would be for any other child controls. You'll need to add some code to check where focus actually is, i.e. on the parent or a child. I would expect that using the ActiveControl property would be a big part of that, but I haven't tested to see exactly what would work and what wouldn't.