I had to look up who Emily was too when people talked about her being the focus of the next update as well. And I had forgotten her name for exactly the same reason you did. I fast forward through her sex scenes or avoid them if the game lets me now. I also find the character's sister boring, which is strange because brother/sister incest is my favorite. But there's something about her character, or maybe it's less fun when the brother and sister are so far into adulthood. I think part of the fun of the incest fantasy for me is that one or more of the participants is innocent and is being seduced, corrupted, or whatever.
My take on the entire A69 thing is that Luxee wanted to have a trap character in PL. There was even a poll, but it got voted down. But he couldn't get the idea out of his head, and just became worse. So A69 is his chance to go with that, since I heard it has a trap in it. Or it may be that he, like other developers, seem to be worried about having a game tied to incest or young-looking characters, even with the current patch workaround. A lot of developers seem to be trying to diversify into games that are safely removed from incest and other taboo topics.