Character Shift Within Venus in Furs

I think it is very interesting that Vanda switches roles from Dunayev to Kushemski at an opportune time in order to maintain her power of Thomas.  First, it seems that Thomas has gained the power as he resumes the role at Dunayev and continues to treat Kushemski as a slave. But, as we read on, it is clear that Kushemski eventually gains control over Dunayev, therefore giving Vanda control throughout.  I think it is interesting that first a woman in the play written by Thomas has power until the end, but in the actual play, the woman seems to have power the entire time.  Even though Thomas is the director, he takes orders from the actress.  I can’t quite articulate what this implies.  What do you think I sthe bigger meaning between the shifts between man and woman roles as well as the subsequent power shifts?