Hawaii Bound - S4-E1
Trivia: Greg's surfing accident - which to this day still scares Barry Williams every time he sees it - was nearly left out of the episode because it was deemed "too frightening for the nature of the show". In reality, he was able to turn around at the last minute and while avoiding hitting his head on the exposed coral, his feet became, in his words, "hamburger meat".
Answer: Much trivia has been written about "The Brady Bunch, " including the various interrelationships and dynamics among the members of the cast. For example, much has been written about why Robert Reed's Mike Brady did not appear in a couple of episodes, including the series finale, due to rancorous creative and artistic differences with series creator, Sherwood Schwartz. However, in contrast, I have never run across any reasons given why a particular child did not appear in specific episodes - only that the episodes were missed. This suggests the causes were likely unexceptional, such as illness, injuries, vacations, or real-life family obligations.
Michael Albert
Although those options ARE possible reasons, it just seems a bit ironic that this happened all in Season 2 ONLY and within a short amount of nearly consecutive episodes. Never happened during the other 5 years of the show at all.