HI Jorosza,
I hope it's not the best practice as well as it's not possible. What's the need of this requirement? You register confirmation details but don't want to do GR, for example order qty as 1000 you done confirmation on yesterday with 400 qty and today with 600 qty. As per your statement you have to do GR with today date with the whole qty 1000. What about your production qty with yesterday date? let us know your exact requirement to think about the alternative solution.
Thanks