Q: How to remove photos from Photos app without breaking Journals in iPhoto

I created a Journal in iPhoto with photos I imported to my iPad from an SD card using Apple's camera connection kit. I made a beautiful journal and posted it to iCloud. So far so good.

By the end of my vacation I had gigabytes of photos, only a handful of which I had deemed worthy of including in the Journal. These were the best photos, the ones I wanted to share with friends and family anywhere I take my iPad. Thinking that iPhoto had made a copy of all the photos (originally sourced from Photos app) that I added to the Journal, I deleted the originals in Photos app to free up space.

Now most of these photos appear as grey squares when I view the album.

The good news is that all these photos are preserved in my iPhoto library on my Mac.

How do I restore the photos that I removed from my iPad such that my Journal will be whole again? I would hate to have to recreate the Journal from scratch--I spent hours assembling it.

Looking down the road after I've resolved the immediate crisis, what is the best way to clear up space for photos that I don't want to carry with my everywhere (I.e. all the photos I'd imported into Photos app but did not include in the Journal) without accidentally breaking the Journal?

(Suffice it to say I find the relationship between Photos app and iPhoto's libraries is utterly baffling and the most problematic part of iPhoto, which is an otherwise fantastically powerful app once you get over the initial learning curve.)