Suggestion: Ability to sell slave!Serena to the brothel.

I have tried both of these situations on a NE play through. Meleny does stay at the brothel or with Mona. When you go back to either location, you can talk to her and she will complain about what you did to her. If you trade her at the brothel, her father does learn of her situation. If you visit him, he will be distraught and then go KOS.

I suppose that it has been a while since I did this and it was before Mona would move indoors. So I'm not sure what happens now with Meleny if you trade her to Mona.

 

I go and pay for her, but I don't get the option to pay off her debts with an LE PC in an NE party, in fact, just like the LN group I just tried, after I let her go and there is no dialog for Ophelia (aside from saying I've solved the Riana problem if I ask her if she is having trouble) and talking to Riana again offers joining her or saying goodbye. Had the same problem with the LN party I tried it with before.