Let there be Auto Sync Copies and Auto Sync Stack!
One of the most mission-critical features of Lightroom are virtual copies and the syncing of settings (copying/pasting from one photo to another). Everything works well until you actually expect for the copies to function as copies. I'll explain.
Currently, a virtual copy is an actual LR copy of another image only at the moment of its creation. Once you make any changes to it, that "virtual copy" is no longer a copy, it's just a virtual reference to the original image with whatever additional changes you made to it. It somehow reminds me of the Stamp Visible feature in Photoshop. You make a copy of the state of things at a point in time and then work it further. Whatever changes you make to the layers below will never be visible. Let's just call it a fork.
I propose that virtual copies get some kind of redemption to live up to their names of being a "copy", with a feature boost that enables Sync Copies to auto sync!
Here's a main example scenario: I have an image that is fully developed and I make a virtual copy to try a different aspect ratio. This image is flagged as Picked, color labeled Green and rated 5 stars. I make a virtual copy of this image to have a version in 16:9 crop ratio, and another square. It could be I may also try a vertical crop, instead of landscape. I now have the same image in 4 different crop flavours, except these copies may not be flagged, color labeled or star rated. This is because if I filter a folder or collection to see flagged images from that shoot, I don't want to see the same image 4 times.
Now, if after creating all these copies I need to make a change to the master image, to maybe bring it more in line with other images from the shoot, I have to manually update all the virtual copies by either syncing or copying/pasting settings, except the crop.
But to update the virtual copies I have to be able to select them by making them visible through resetting my library filters to not show only picks and green labeled images.
Here's another kicker: what if the master image I work on is in collection A that holds all my picks from the shoot, my 16:9 crop copy is in collection B (that is synced to show on my TV), my square copy in collection C (for a special book project) and my vertical copy in collection D (shared with a client for magazine cover candidates)?
In that case, the only way I can go about selecting my master and copies together is by getting out from whatever collection I am in and going to the folder in library, selecting there, and auto syncing or copying/pasting the needed settings and resume my work. And that has to happen for any image and every time a change is needed after the virtual copies are created.
Or, I recently found out about this feature hidden in Develop > Settings menu > Sync Copies (and which only appears there (not in the contextual Develop Settings menu while in Library module, and not under Photo > Develop Settings menu while in Library module). Using Sync Copies greatly helps, but I still have to remember what not to sync from one (master) image to another.
Why does it have to be so twisted a workflow?
The need is simple: 4 images (3 virtual copies and 1 master) should be in sync all the time, wherever they may be found, in whatever collections, minus some key adjustments, like crop (in this case).
I would like to be able to go to the master photo, select Settings > Auto Sync Copies..., choose everything I need synced, minus whatever I don't need synced and not worry about further syncing settings. If I make any adjustments to the master, it will automatically be applied to all copies, minus the crop.
Imagine if you had to click a button to resync an image that is in a synced collection, every time you made a change to the image. If you forget, whole collections would quickly get out of control. Or, if we didn't have smart objects in Photoshop anymore. Insanity.
For more flexibility, like in the case where you need certain copies auto synced and others not auto synced to the master image, this logic can be extended to stacks, so that auto sync will apply only to copies in the same stack as the master image, or simply, configure the first image in a stack to auto sync to the rest of the images in the stack (regardless of whether it's a master or copy). Maybe this could be called Auto Sync Stack ;).
If you reorder the stack by setting another image as the first in stack, when the stack is configured with Auto Sync, there would be a prompt to the user (similar to the one shown when trying to make changes in soft proof mode). The prompt would ask whether you want to disable Auto sync for the stack and set another image as first in stack.
Attached are some mockups to give an idea of some UI elements that could indicate whether an image or a stack have auto sync enabled.