Looking for an old series – office slut training

This was a rather large series, upwards of 50 parts if I remember correctly. It was about a girl who worked at an office that trained her to be a slut/slave with ranking systems, special IDs, and progressively harder core home training. I think her younger sister also ends up joining the company. Any one got any ideas?

Source: reddit.com/r/eroticliterature/comments/8wi7b6/looking_for_an_old_series_office_slut_training