iCloud Photo Sharing is all Apple has to offer to share photos, but it has many draw backs. It is fine to show off the best photos in shared albums and to transfer them easily, but it it is horribly inadequate to share a joint Photos Library between family members.
- We cannot sort the photos in the shared albums.
- The number of photos and albums is listed.
- And worst of all, most metadata will be lost, when we add photos to a shared album and the quality will be reduced,
When shared, photos taken with standard point-and-shoot cameras, SLR cameras, or iOS devices have up to 2048 pixels on the long edge. Panoramic photos can be up to 5400 pixels wide.
Shared albums cannot be used to transfer photos to a joint family photos library, unless we want to sacrifice image and video quality and metadata.
Even with shared iCloud Storage planes, the only supported way to share a Photos Library is still the sneaker drive: Sharing photo libraries among multiple users - Apple Support