do you think Sandor will contribute more as Opp since it was her original position and Nika&Mlejnkova is a good OH duo anyway
That is really hard to tell: none of the three ever played (sub) Opp in Stuttgart, so it would have to be tested. I don't know, if they try it at training, but it seems possible - during ball training dual license Große Scharmann can also act as opposite, so there is no need by itself for this approach.