2 Kobos, 4 users with shelves & progress sync, highlights to Readwise. Possible?

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We're a family of 4 with 2 Kobo Libra2 devices. We all want to use them. We may add a bigger e-ink device in the future and will also want to share that.

So far I've set up Calibre with a single library, and Calibre-web with 4 shelves, one for each family member. I have created 2 Calibre-web users, each of which is attached to one Libra2.

That gets me a single centralised library, and I can add books to the kids shelves from the comfort of my PC using Calibre-web, knowing that it will sync to the device overnight without me having to do anything else.

The downsides are,

1. Each shelf only syncs to one device, not both. Even if the shelf is marked as public and set to sync for the 2nd Kobo user, it still only appears on the 1st device. So if I want Kid1Shelf to appear on both devices I have to work around it by creating 2 shelves, Kid1Shelf-KoboDevice1, and Kid1Shelf-KoboDevice2
2. I don't think I can sync highlights to Readwise or any other highlight manager
3. I don't think I can sync progress for each user.

I have installed KOReader, and I can export highlights to Readwise. I have also read a thread about installing multiple copies of KOReader and creating a menu item to launch a copy for each user, which would let me store the sync progress for each user.

But, I've not found out how I can manage a subset of the library for each user from a PC and then have it easily synchronise with each device. The dropbox integration for example appears to need a manual send of each book to each device.

Am I missing something? Is it possible to get library management, multi-user, and highlights using either Kobo Reader or KOReader? Thanks.