A lot of people have wondered what had happened to Richie's older brother Chuck.He seemed totally forgotten by the time they began filming Happy Days infront of a live audience.The way I see it,what made the first season so different from the rest of the series,besides the fact that it was before the show became a live TV sitcom,is because they're two different versions of the show.The"Brady Bunch"type version,where there was just a laugh track,and the live version.There scarcely seems any relation between the two.It seems that the first season had been set in a different universe from the rest of the show.I guess the writers had decided not to include the character of Chuck Cunningham in the live version.Which now made Richie the oldest child in the Cunningham family.:D

Even when Chuck was on the show, he wasn't really there much. A lot of times they just mentioned him. He only appeared in 7 of the 39 episodes of the first 2 seasons. His last appearance was in the Christmas episode from 1974, right at the time Fonzie started to be like a member of the Cunningham family.

Chuck was mentioned during the third season (when the show was filmed in front of an audience). They were doing a flashback to the 1974 Christmas episode, and as Fonzie "introduced" the flashback, he mentioned that Richie's older brother Chuck was home for the holidays. That scene is never used in syndication, though -- the Christmas episode is aired as it was originally.

That was actually from the 4th season believe it or not, and it started out with Al feeling as though he would feel out of place at the Cunningham's Christmas party, and Fonzie explains to him about the Christmas he spent there 2 years earlier. This version was actually shown on the TV Land Merry Thon this past Christmas. Come to think of it, I think both versions were used.