Try this first - take some of the Sherwood and put it in a separate container. Add some water. Let's start with 1:4 (1 water to 4 ink) or something fairly conservative like that. Mix it well (don't need to shake like mad, just a little swishing) and load your pen. Try that for a few days to see if it still flows well, has the color you like, but doesn't smear as much.
In *general* most of these smearing inks are leaving excess dye on the top of the paper rather than soaking in. *In general* many of these inks have enough dye in them that even a 1:2 mix doesn't grossly alter the color (but might alter flow and bleeding/feathering properties.) I think someone here mixes water and PR Plum 1:1 or 1:2 and still gets a bright saturated color - someone can correct me on that if I'm wrong.
Give it a shot. If 1:4 doesn't work, adjust it whichever direction and if none of that works then I have no recommendation other than Diamine Woodland green with a dash of black ink.
just some thoughts.