This first episode is obvious filler, not much interesting happening, nothing to advance any plots, certainly aids the claim this episode was a last minute insertion.
This clears some things up for me. The episode guide on the Emmerdale Farm wiki has the same synopsis for the episodes originally shown on 23rd Dec 1993 and 28th Dec 1993 - the events of 28th Dec episode are not summarised. Also, the person who uploaded the Granada Plus repeat of 23rd Dec episode onto YouTube has erroneously labelled it as 28th Dec and “last episode before the plane crash”. So this is the first I knew that another episode existed set on Christmas Day, which led to my previous confusion about how much time had lapsed between the events of 23rd and 30th, and what date (in Beckindale time) the plane crash occurred. Events did seem to jump from pre-Christmas (23rd) to post-Christmas (30th) but the storylines continued quite naturally. I assume that’s how they originally intended to show it - nothing in the episode from 28th Dec particularly advanced any plots, and it does stand out pretty obviously as a filler. This also explains why New Years Eve and New Years Day aren’t mentioned in the plane crash aftermath episodes: the crash was originally going to occur on 28th Dec with the following episodes depicting 28th through to 30th, whereas we can now assume they depict 30th Dec to 1st Jan 1994. When Frank says to Kim (in the episode we see next Monday, originally shown 6th Jan 1994) “It’s been a hell of a year” this is now the final scene set on
New Years Eve 1993, originally it would have been set on 29th December - so the date change makes his comment pretty apt for New Years Eve!
By the way, did any of Seth and Meg’s children ever appear? I notice that Meg’s gravestone reads “A dear wife and mother”.