<Putting on Sherlock hat>
OK, we all know that Shemp only appeared officially with Fields in The Bank Dick, which is another movie altogether, but the eager way you posed the question suggests there's a surprise "yes" answer here. I also recall from my viewing of Sucker a couple months ago that Fields can be seen at the beginning of the movie gazing up at a billboard for one of his old movies, which I'm pretty sure was The Bank Dick.
SO...was Shemp's mug on this billboard?
Eh? How 'bout it?