Working with expanding sprite sheets that shift around?

I'm curious of perhaps some better workflows when working with expanding sprite sheets like doodads/etc. Sometimes the order inside the spritesheet gets chaotic and unordered as I get new ideas and new art. If I rearrange them so the order makes more sense, then I'll create a ton of work for myself to fix these changes in Unity. This also leads to me having a bunch of spritesheets that are expanded vertically so I can "some day" add more sprites horizontally that are related. Is there perhaps a third party program where I could organize these and it would perhaps keep the individual sprite names and slices when imported?

What do you do? Do you just leave your sprite sheets alone once you start using them?