Selective Photos sync via icloud
I've been successfully synching the Photos app across my MacBook, iPad and iPhone via iCloud. However, now I'm about to convert my Aperture library to Photos, and I don't want those thousands of images synched. What's the recommended way to synch photos selectively? The outcome I'd prefer is that new photos created on the IOS devices will show up on all three devices, but photos imported on the Macbook will not do so unless I "push" them.
I'm on IOS 11.2 and OSX Yosemite (older MacBook).
OBS MacBook (13-inch Early 2009), OS X Yosemite (10.10.5)