iCloud photos

I have an iMac at home, a MBPro for the road, an iPad, and an iPhone.

All on +

All signed into iCloud

All using iCloud Photos “On”

iMac is at home, but I have extended maritime trips with the other devices where access to the internet is spotty, if at all, for weeks at a time.

If I have 10,000 photos and delete 1,000 using the MacBook Pro, iPad, and iPhone, signed in but not online, will they reappear because the iMac was online?

Or vice versa, if I add 1,000 images to an offline but signed device over say 2 months, and the reconnect, will those images transfer to iCloud and the home iMac?

The iMac and MBPro store all “Originals”, but the more mobile devices are “Optimized”.

Curious and a little concerned how iCloud Photos work when syncing if some devices are not persistently online. The MBPro in particular may only be online 3-4 times per year, for a few weeks at a time, but with long gaps where there is no signal to sync.

Thanks.