Not sure if I understand 100%...but, here goes.
You can generate an SQL statement, to attach to the "RecordSource" property of the subform, to filter it accordingly.
SQL = "SELECT tblProducts.* " & _
"FROM tblProducts " & _
"WHERE tblProducts.ProductID =" & Me.ProductID & ";"
ProductDetails.Form.RecordSource = SQL
or, use the filter property of the subform.
ProductDetails.Form.Filter = Me.ProductID
ProductDetails.Form.FilterOn = True
I believe, my syntax is correct in both cases.
I used "ProductDetails" to reference the subform, it should be whatever you called it on the main form, not necessarily its actual name.
Hope this helps Rakesh, good luck!