Rozalind Pankiera is tied to the quest
. When you talk to Dandelion in the New Narakort Inn (in the
), he'll tell you that he had to leave his lute behind in the merchant's house (also in the
) when the merchant discovered him giving "lessons" to his daughter Rozalind.
Inside the merchant's house, after dealing with the merchant, you'll find Rozalind upstairs in her bedroom. She'll immediately approach you and start a conversation. If you take the dialogue branch that begins with "That's why I'm here," and then later say, "If you give up the lute, it'll prove he's nothing to you," then she'll agree to sleep with you.
Note: You'll find
in the trunk in Rozalind's bedroom. If you pick up the lute and trigger Dandelion's quest that way (instead of talking to him to get it), then you won't receive the right dialogue options to sleep with Rozalind.