Adding additional Sprite frames?

I don't mean just changing to a different sprite sheet. I mean, for instance, if one wanted to add additional sprite frames to the walking animation to make it appear smoother, 6 frames instead of 4 before the animation repeats. Well, actually that's not really what I'm interested in, more like event things, for instance Cyan having frames of him just actually grabbing his nice silk flowers instead of jumping in place while using his secret telekinetic powers to make them slide down to his sprite.
Is that feasible at all? However convoluted it may be, and I really do mean no limit on convoluted. If it really is simply impossible can someone explain to me why?