Hi Dan,

For me it is not the best solution to alter the query at OnCurrent event.
Because this procedure is triggered every time an action is performed,
including actions not in relation to your subform.

What I have done is indeed create an unbound child form and alter the query
while doing some action (like pressing a form button, combobox whatever) the
recordsourde for the subform changes and the new data is displayed.

what you could do fe.

create on the master form a textbox named TAGID
 within the code
Option Compare Database
Dim sSQL, sSQLField, stDocname As String

Private Sub BtnPC1_Click()
Me.TAGID = Me.BtnPC1.TAG
QCONTENTPC
End Sub

Function QCONTENTPC()
sSQLField = "(((Software." & TAGID & ") = Yes))"
sSQL = " SELECT Software.*, Disc.DiscName" & _
      " FROM Software" & _
      " INNER JOIN Disc ON Software.DiscID = Disc.DiscID" & _
      " WHERE" & sSQLField & _
      " ORDER BY Software.ProgramName;"
   CurrentDb.QueryDefs("Q-ContentPC").SQL = sSQL
Me.PC_Content_subform.Form.RecordSource = sSQL
end function.

To use this for a bound form is more or less equal.
first you need to open the form, and secondly you can define the
recordsource for that form.
fe:
DoCmd.OpenForm "BoundForm"
Forms!BoundForm!.Form.RecordSource = sSQL

good luck
Harry