Best of Both Worlds by River Lynn and Kay Lovely from Dadcrush.com
Calvin discovers that his stepdaughter, Kay, has been sneaking in her secret girlfriend, River, to have sex. Calvin decides to invite River over for dinner so he can at least get to know this girl and figure out what’s going on with her stepdaughter’s sex life. Kay confesses that she doesn’t know if she likes cock, pussy, or both, so Calvin kindly offers his cock to help her figure it out. Things get steamier once River proposes the best solution to determine Kay’s sexuality: a threesome.