Is this a main form/subform(s) design? The main form is for a parent record (e.g. PO) and the subform is for the related child records (e.g. PO line items). Existing line items should appear when looking at a PO and you add new line items if it's appropriate.
Regardless, it seems you have a disconnect between the parent record id and whatever you're doing after that form is open but I can't see your design.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.