Robert Taylor's Musicians: Reflections of Music-Making is a collection of drawings by Robert Taylor of musicians from many traditions and backgrounds. His list of pianist sketches contains many of the collaborative sort, mostly drawn in performance at Riverside Church at NYC.
Recital sketchers are a rarity indeed. There was anonymous sketcher in Toronto that I encountered three years ago at a recital I played with soprano Jennifer Rasor at the University of Toronto's Walter Hall. The final piece on the program was Villa-Lobos' Bachianas Brasilieras #5 for voice and 8 cellists, and following the program an elderly man handed Jen a brilliant line drawing of her performing with the 8 cellists, and then walked off into the Toronto night.
Sketch of Ron Metcalf by Robert Taylor hosted by Teachers College, Columbia University