In the subform's "on dbl click" event just reference the opening of the editing form...e.g.,
'filter search criteria according to user selection in 'subform...this routine uses the RecordsetClone property
'of the form to take advantage of the FindFirst method
Dim MySet As Recordset
Dim StrCriteria As String
StrCriteria = "[My_ID] Like'*" &_ Forms![MyMainForm].Form![MySubForm]![My_ID] & "*'"
'note the Like statment allows partial string searching..
'not necessary to use this if an exact match is expected...
Set MySet = Forms![MyEditForm].RecordsetClone
MySet.FindFirst StrCriteria
Forms![MyEditForm].Bookmark = MySet.Bookmark
Forms![MyEditForm].Visible = True
DoCmd.Close acForm, "MyMainForm"
Exit Sub
'if the ID field is in the subform this code assumes it's in the Edit form as well..