The new Lightroom CC would be ideally suited for family use. A shared family photo library in the cloud can be built and maintained. The mobile devices (iPad, iPhone) can be easily integrated already.
Not so for PCs: The installations are limited to two. Even when an additional subscription is purchased, it can't be integrated with the existing cloud based photo library (one gets a new, independent one).
Please allow a reasonable set of PCs to access the shared cloud photo library. A ballpark number would be 5 (similar to the Microsoft Office Family License).