I'm transcribing a piano piece. There is a short note that should be attacked slightly later than notated, but should not be played fully as a grace note—rather somewhere in between. (Even playing by ear I have to be careful to strike the right balance so it doesn't sound weird.)
I'm not trying to nitpick exactly when to strike it, but I would like to give the performer some indication that it is a less important note. I just can't find a good way, precedented or otherwise, to make that visually clear.
Is there any kind of established convention for this? If not, what similar ideas could be modified to coin something intuitive?