I think at this point that nobody will do this very long hell of a run, but (this question is for the mods) can a category begin with a relay as a subcategory?
I think it can and it should be perfectly alright. It will cause a minor name change of the category once a solo run gets completed and submitted but should be perfectly alright. (Name change referring to the idea of having "Relay" as part of the category name, as long as nobody does a solo run) Of course there is the arbitrary limit of wanting to see 3 different runners to go and complete a run of it so it makes sense to even have a leaderboard list them on SRC. That rule only not getting applied when its not really part of our core community and rather fitting to a different Mario community but without a place to exist on. I did change the Archives sheet a little so we can list all categories that have not made it to the CE board there together with the achieved times.
You can now submit runs to the 602 and 1862 leaderboards under the TA filter if you took breaks for sleep and paused the timer! Rules will be more in depth on the category pages on the leaderboard.