I just graduated the Best of friends household sans Summer Holiday that I had added to that household earlier, and neither of them got a diploma, only the graduation photo.
They are counted as having had graduated and I have move them out (didn't get any prompting to do so though) and I got Becca (haven't gotten Julia a job yet) a job as a lawyer and I found that I could get her the author job and the Private Attourney branch jobs easily with her degree and she got a signing on bonus as well...
Is it maybe because Summer, who is still attending university was present? Or an attendee and living in Wyvern dorm with them when they graduated? Because they don't have a degree I don't know if they graduated with a normal Degree, a Distinguished Degree, a Degree with honors, or Distinguished Degree with Honors. One of the got a B- and the other A- though (can't remember which got which though).