Other than the Rush adoption, this was the most important episode

 
If you will think about it a while, I think you will find that the second most important episode is 410123 The All-Star Marching Team.  It trails only Rush's arrival.

The reasons for this include the fact that for a good part of 1941, the marching team was mentioned quite a bit on the show.  The January 21st episode mentions nine new characters, four of which would go on to become quite important in Vic and Sade lore.  That's not even including Y.Y. Flirch, who was important to the show before and after this particular episode.

Overlooked by me until yesterday, I realize now that the Hink twins (Robert and Slobert) were apparently already a part of the show before this episode, because Sade says to Vic, "Robert and Slobert are a couple more fellas that are always shovin' themselves into stuff."  Always tells us that that the Hink twins have been mentioned in previous episodes and those obviously had nothing to do with marching team business.  We do know they were Christmas card salesmen in 1940.  It may also mean that the infamous power mower episode may have also taken place that year.  And it probably also means that the twins were in other episodes that we don't know about and they may have come before the original All-Star Marching Team episode.

This may not be an earth-shaking revelation (to you) but to me, its important to know that the Hinks may have been on par with Flirch as far as popularity goes.

As I mentioned, this episode spawned many new characters.  Many would become fixtures on the show; besides the Hink twins, Homer U. McDancey of East Brain, Oregon and H.K. Fleeber of Grovelman, South Carolina become the basis for many programs.

The marching team concept leads to all kinds of other scenarios and episodes: McDancey writes a book on the rules of the lodge for wives.  And he is so obsessed with marching that he tries to lure Vic into marching solo at several homes for various peoples with "ailments."  That's not just one episode, but two known. And of course, other marching team episodes exist: the threat of Sade having to march, the botched photos in the lodge quarterly, solo marches, unity of the team being destroyed and on and on.

Fleeber is just plain wacky, and his odd exploits are thick.  He's used often in the series.  But it's not just Fleeber, all of the All-Star Marching Team participants are a little loopy, which brings into question Vic's own sanity.

And of course the Hinks themselves, their phone calls, their twin relatives with the unusual (and funny) names and their subsequent feud with Vic provides us with tremendous fun and leaves us wondering how it all went so wrong.

The marching team concept (and the episodes about it which follow this one) carries so much weight in the history of Vic and Sade that it seems impossible that writer Paul Rhymer could have come up with this concept in his usual two or three hour writing period.  We'll probably never know if this is true or not or how and when the whole idea was conceived, but what we can know is that the original marching team episode remains one of the most-important installments in the history of the show.