[AccessD] How to transfer text..

hi group,
On a double click on a form I use the follown:

Private Sub AM_DblClick(Cancel As Integer)
Dim poustia As String
Dim stdocname As String

stdocname = "MT_basic_char"
    If IsNull(num_mitroou) Then
        DoCmd.OpenForm stdocname
        DoCmd.GoToRecord acDataForm, stdocname, acNewRec
        else        
        poustia = Me!num_mitroou
        DoCmd.OpenForm stdocname, , , "num_mitroou= " & poustia
    End If
End Sub


what I want to do is after the new record update  and closing the stdocname
the text of AM's field to be tranfered  to the AM field of the opened form

Many thank's
/kostas