There's not a completely fleshed out prostitution path for them, but there are ways to get them to go out!
For Anya, after finishing her story call her on the comm and you can start her side story, which involves her playing with village men.
For Eillana, after finishing her story talk to her at night in her room with no other events running to start her side-story, which involves a series of misadventures in search of a way to increase her magical power! (And this eventually leads her into, among other things, playing around with village men!)