Right now, the majority of "Instances where Vogel fully performs Big Bird" on Vogel's page are already on the transition page, plus a bunch more (especially re appearances and commercials). "Smarter, Stronger, Kinder" is one of the few only on Vogel's page. The "Instances where Vogel performs Big Bird to Spinney's voice" section is only on Vogel's page.
So for practical purposes, the options seem to be just move everything not duplicated save the explanation text and a See Also to the transition page, or just keep the performing to Spinney's voice portion (which mostly has more detailed notes). But right now, it doesn't make much sense to copy ourselves.
I never really liked that list on the Matt Vogel page as it's just an overly long section for a performer page, and the examples used aren't really sourced other than perception of a given episode. I tried to double-check them and clean the section up the best that I could, but I honestly feel like it's better suited as an add on to the Spinney character transitions page or something else.