Here are a few ideas on how to personalize shared events:
1) Journal to one person in particular (it can be as short, simple, and subtle, as the tag above)
2) Tell the story from one person's perspective (P was climbling the tree while the others were watching the ducks)
3) Feature a favorite acitivity, unique to the person. (tree-climbing)
4) Feature photos of the person you have in mind. Note that I still include J (and I'm going to include this same tree climbing photo of J on his own page, just b/c I like it so much and I think it makes a fun "following in their footsteps" theme).
I think this approach to scrap separate personal pages as you go along, makes it less overwhelming to scrap for multiple children (in the end, my kids will each end up with their own albums, without me having to be intentional about it); *and* it makes it more fun, since I don't repeat the same layouts, or even photos. It's also a thrifty way to scrap - since I tend to take this approach when I end up with at least several good photos of each of the kids, I would otherwise be scrapping 3+ pages anyway. Most likely, the pages will be somewhat coordinated, so you will end up using what you have (versus buying pages later on specifically for her *special* scrapbook).
This is just my opinion, of course. My point is to find out what works for *you* and just scrap it...don't get stuck in the planning phase! Tomorrow I'll post the other two kids' layouts of this trip, which will include thrifty layout tips!
Let me know what you guys are doing... I would love to get, and share, new ideas!