As for seniority, there was a precedent, albeit not recently, for Squadrons re-numbering on disbandment of a more senior squadron to preserve the identity of the more senior unit. BUt I think they stopped that in the mid 60s.
Not that this is of any significance compared to the main issue of the thread, but I think this has happened more recently than the 60s eg 27 Sqn renumbering as 12 Sqn in 1993.