No luck. It doesn't work. & 'NordersDetails' is the name of the control as well as the name of the subform on the forms section of the db. I always try to make them identical to avoid problems.
I also tried this (although I knew it would not work either):
[VBA]
Forms!NordersMaken.NordersDetails!Order_Details.ProductId = Me.ProductId
[/VBA]

when the form opens it says that it could not find the product.Id (or the Order_Details.ProductId).

I do not know what is you other idea, but I've read somewhere that it could be useful to use OpenArgs, something like parent.OpenArgs maybe? I don't know how to develop a code for this. What do you think?