Uploading Photos to iCloud

So I've got in a bit of a muddle with my photos. Currently in our house we have:

• A 200GB iCloud Storage Plan
• 2 x Iphones (latest IOS) and an iPad Air 2 with seperate Apple IDs but family sharing on. We regularly take photos and videos on all of these. All are syncing/backing up to iCloud
• Macbook Pro 2013 with docs syncing to iCloud
• A Windows 8.1 PC with a large quantity (around 80gb) of photos on an external Hard drive in folders by years. This PC has ICloud Drive but as far as I know no photos are syncing up to iCloud. However within my Windows photos folder I also have a iCloud Photos folder which looks to have photos from one of the iPhones up until a couple of months ago (no idea why!).

The PC also stores a lot of our music so we use it to sync via USB to the iPhones through iTunes.

What I am trying to achieve is to move all the photos from the PC into iCloud in a sorted way so that I can access/edit them in MacBook photos, through the iPhones/Ipad, back them to iCloud, view on the PC and not clog up any of the individual devices storage.

Can anyone offer a route through??

Thanks!