This worked for me, as my shared "Screensaver Album" (1100 photos) would add photos that I added to the album, but never removes the photos I had removed.
However, this approach is a work around for a missing fundamental feature. The weakness is that signing out removes ALL photos down to a black screen. Signing back in then starts a process of loading ALL photos all over again. In my case, it took well more than a half hour to restore or reload my 22,000 photos when all I wanted to do was get one shared album to update about 50 photo revisions!
I am sending in the suggestion to Apple programmers that they provide a more efficient "update album" kind of feature instead of a "wipe it all and start over" none-approach. They do a great job, in my 38 years of experience as a user,(starting when user meant programing for yourself in basic and saving it on a tape cassette), but we users will always find problems … always.
MacBook Pro (15-inch, Late 2016) MacOS 10.12.4, with latest AppleTV (4?) and its up-to-date OS. Using iCloud Drive.