How can multiple iCloud users in a family sync photos on a single Mac Logon?

My family recently moved from a single Apple ID for iCloud to a Family program with multiple IDs. This has worked very well for separating things like contact lists and for sharing iCloud storage. However, it doesn't allow us to automatically sync photos taken on our devices with the Mac Photos App. Only photos taken by the primary iCloud user associated with the logon for the Mac appear. We continue to share a single logon for our Mac, as this is most practical for our home. We would really like to know how to add photos from the devices of other family iCloud users for editing and sharing in Photos on Mac.

Photos on Mac has made a lot of progress and is something we're now using again in macOS High Sierra. Does anyone know of a way to sync multiple iCloud accounts to Photos?

Thank you!