She can go whenever she wants, just not for the OG.
And I think that Witkowska can go to Paris not only for a trip.
For me Witkowska can be a "joker" player as Mędrzyk. And she proved it last year in the POL-ITA qualifying match. Even in the last match against Japan she was very useful in a difficult situation after Korneluk's injury. I really like how many rebounds and good touches on the net Witkowska had.
Moreover she is the only middle blocker in our roster who uses one leg attack (and thanks to it with Witkowska as a substitute player we can for example change our style of playing during the game).
This is why I think Lavarini will take her to Paris. In my opinion the 3rd middle blocker will be Alagierska or Jurczyk as they are similar type of player.