Edit at multiple values of a shape key?

So yeah no? Is there a way to animate multiple points of a relative shape key or not?

It doesn’t seem unreasonable given there’s already a keyframe feature built into blender.

If you still don’t understand the issue, imagine a simple translation. At at shape key value of 0, it corresponds to your basis. At 0.25, you decide to move the vertices left by 1 unit. Now normally, blender would automatically apply this transformation at 1.00 for reasons beyond comprehension.

HOWEVER, suppose you want to also have the vertices then move up by 1 unit at 0.50, then move the vertices right by 1 unit at a shapekey value of 0.75, then down 1 unit at 1.00.
Then at 1.00, the vertices should be exactly where they started, but if you animated that shapekey value between 0 and 1, the vertices would run through the translation cycle.

This effectively bakes a small animation using the deformation itself so that you don’t have to composite it over several different shape keys but will still be composable with other shapekey deformations. Is there a way to do that?

No, shape keys don’t contain that kind of data. For what you’re literally describing, you would need multiple shape keys and a driver to control them. But really, you should be looking at different deformation techniques, like an armature, and possibly an action. It sounds like you’re trying to use the wrong tool for the job.

I do need to create multiple shape keys, but I think there is a way to control all of them at once with one parameter, using some kind absolute shape key thing. That way I wouldn’t have to constantly copy their dope sheet values and modify them each time.

Yes, what you’re looking for is a driver. The parameter driving the shape key values can be anything you want, including the value of an empty (no edit) shape key.