I created two photo books on one Mac, but that Mac is getting a little constrained on space (this has now actually become more important, because I can not update to El Capitan because there is not enough space). Eventhough I've set Photos to "optimize storage", its library is almost 50 GB and I suspect my two photo albums are partly to blame. Regardless, I'd rather move these projects to the Mac that contains the full ibrary for safe keeping.
Is there any way to do this? I can't find any "export" option, or some such.
I asked the same question over on the Apple support community, and the answer was it can't be done. The same answer is given to a similar question on here, but for iPhoto (How do I move an iPhoto '11 book project from one mac to another).
However, when I open up the library using "Show package contents" I can actually see what appears to be all the data associated with the projects in resources/projects. I've tried copying one of those directories into the target Photos library, but as soon as Photos is started, the copied directory is removed. It seems that if only I could set the right metadata somewhere, this should work.