This is actually pretty hard. You either have to just accept the lower resolution you get with Whatsapp or iMessage, or you have to go to great lengths to share high resolution photos. here's a guide...
If you don't care about privacy and let Google index everything you own:
- Also if you want full resolution, you need to pay them $10/month for Gsuite which amongst other things gives you 1 Petabyte of Google Drive
- On your iPhones, run Google Photos and it will upload everything
- If you have any photos you process from other cameras, run Google Backup and Sync on your Mac or Windows machines and click on Upload Photos to Google
- Now you go to Google Drive and say you want Google Photos included in Google Drive. This way when you do a sync downwards, you get all your photos.
- You can now in Google Drive copy them out. The nice thing is the file names are notes <date>-<time>.jpg so they are easy to manage.
At this point, on your main backup machine, you can download all your full resolution photos from IOS, Android, Windows and Mac for $10/month. Not a bad deal.
If you do care a little about privacy you have to go the other route and throw everything into the Apple world. This is a little more complicated mainly because Apple doesn't have a Google synchronizer, but here are the steps:
- Buy the Apple iCloud Family Sharing Plan. For $25/month, everyone in your family gets unlimited storage.
- Now all the photos on all iPhones are backed up to iCloud, they are however going to individuals. When you want to share them use Airdrop to get the high resolution photos over to your phone.
- Your Mac of course can see all the photos and if you want to archive them separately use the Export. This is a little more complicated because the original file names are kept of the files (I actually kind of like that), so you have to sort them with directories to prevent collisions.
- Of course if you have Windows machines or Android machines, you are out of luck. What I do is to take the Google workflow, I load Google Photos on Windows Google Backup and Sync and then all the photos will appear in Google Drive. I can then import these into MacOS Photos.