But she can be sub of a sub. :) You can first blackmail her, and then this mean girl Mistress will find out. And you can have 3 choices. Abandon her (only femdom), abandon Mistress (only maledom), or surrender police girl to Mistress. And this can be very humiliating, like you will invite her to Mistress apartment, and she will see you naked and tied under Mistress feet. She will be in shock, but horny. She will submit, and then you can fuck her only with Mistress permission. Otherwise - you will be punished hard.