How to share Photos for OS X library among users on the same Mac?
How to share Photos for OS X library among users on the same Mac?
iMac (27-inch, Late 2013), OS X Yosemite (10.10.3)
I've not seen an update to this so assume that it holds for Photos too if you wan tot share a local, physical ibrary
iPhoto: Sharing libraries among multiple users - Apple Support
And of course if you are using iCloud Photo library then it is automatically shared across devices and accounts that are logged into the same iCloud account
LN