This is a harem containing Samantha and Emma.
Date with Emma at the mall
Prerequisites: Emma's >= 63, Samantha's >= 63, Samantha is divorced, had sex with Emma and Samantha in the timespan of one week. (these are only the conditions to trigger the event, see the conditions below to form the harem)
Mike & Emma have a date in the mall until Sam spots them.
Those are the conditions to successfully form the harem:
Prerequisites: Afternoon or Evening, at least 2 days after "Date with Emma at the mall", Mike is not on a date, Mike is at home, the harem was formed successfully during "Date with Emma at the mall"
Emma and Samantha pay a surprise visit.
(If Mike invites Emma or Sam on a date afterwards he can to go on a date with both girls to repeat the threesome)