Simple. We can group by order states so what we need to do is storing order no as order state and configure printer template accordingly.
Create an action that stores order numbers.
For more fine tuned control it might be implemented differently but the simplest way to update order numbers will be doing it while order status changes from new to submitted.
I added highlighted part to group by order no state. I also disabled line merging so same products from different orders will not merge.
This is my result
