Any word on this case? The mother divorced the husband and "only wanted the girls" The sister found their father who was a former clown Curly for the circus. He had the little boy for 5 yrs and then he was put up in a Catholic home. There was on update on the show itself.

I don't have any info.

The UM wiki doesn't have anything about the update. Was the update regarding Peggy (one of the daughters) being reunited with their dad, but they still hadn't found Arthur? Or was it about something else?

http://unsolvedmysteries.wikia.com/wiki/Arthur_Lloyd

Yes, at least they sound each other :(

Why didn't the mother want Arthur? I know the wiki site says she left Arthur behind as "some sort of revenge," but that explanation seems so vague.

I must say that Peggy Lloyd did pretty well portraying herself in the reenactment. Usually, when the subjects participate in the reenactments of their own stories, they come off almost breathtakingly wooden. Peggy, however, seemed natural playing opposite her "mother" and "father."

As for Arthur's whereabouts, I think he's still alive (or, he was when the segment originally aired), but I imagine that he is/was too hurt over being abandoned to reach out and reconnect with his sister and father. This might have been a case where the "lost love" preferred staying lost.