So, What's the Deal with K and Yukino in 1992?

This damned 5th Anniversary Newspaper leaves me with more questions than answers, once again.

The 5th Anniversary Newspaper's list of lives in 1992.

So, we know right off the bat that K was their first vocalist at the time of the band's formation in September of 1992 up until December 30th of the same year. The newspaper DOES list him in the band's first lineup on the September 7th, 1992 live at KOENJI LAZY WAYS, yet it doesn't mention him leaving the band on December 30th, which I'm once again assuming is an oversight. That is, unless the swap happened earlier than December, which I don't think is the case at all since a live report mentions K performing as late as December 30th.

Yet, when I went to add onto the table of live show dates, I realized that Yukino's name appears as early as October 31st, 1992 at CLUB 24, which struck me as kind of odd since most sources I've seen just list Yukino as their vocalist starting on December 30th. It also doesn't elaborate beyond "VO. 'K' 雪乃". This isn't the only place I've seen Yukino mentioned early on, though - an old fansite also mentioned that the last song performed on December 30th was "the first and last song to feature K and Yukino's twin vocals".

The history DVD aligns with vk.gy and the fansite.

So really, was Yukino there chilling with the band as far back as October? If so, what was he doing with the band since he wasn't the vocalist at this point? The history DVD included with Phantom of the Tenth Year also doesn't elaborate on any of it, so I guess I'm just out of luck unless I ask someone about it.