A key command for adding exposures without sliding the next drawings?

I’m wondering if there is a key command that allows you to add exposures, one-by-one, to a particular drawing, without sliding the next drawing further down the timeline.
For example, say I have a drawing on frame 1, and my next drawing is on frame 7. I want to one-by-one, add exposures of the drawing on frame 1, but keep my next drawing where it is, on frame 7.
Something akin to the plus and minus key commands to add and subtract exposures, but which doesn’t affect the rest of the timeline.

Is there such an animal?