That's Mine!

When you're a multiple, you have to learn to share at an early age: your room, your clothes, your toys, your parents. Overall, my daughters have been pretty good at this, but sometimes they just can't take it any more.
They each have certain things that are theirs and only theirs and I really make a point of enforcing that. Besides their blankies, Tortilla has a purse that she refused to let go of during a recent shopping trip, so Grandma bought it for her. Sue-Sue and Roo each have a stuffed animal they received at separate doctor's appointments. Cakes could really care less about claiming anything as long as she has her yellow blankie.
But inevitably, one of them will find a toy that no one has touched in months and suddenly I feel like I'm a referee for Ultimate Cage Fighting. They will gladly share toys with other children, but are more than happy to see which sister can draw first blood over the silliest things.
For instance, yesterday we came downstairs for breakfast and Tortilla decided to play with a babydoll pillow. As soon as she set it down to grab a babydoll, Cakes took the pillow. Screaming ensued, mainly along the lines of "that's mine!" Usually my rule is this: if you put it down then it's fair game for others. But considering Tortilla only put down the pillow so she could find a babydoll to use with it, well, things were a little dicey. I finally convinced Tortilla to use a smaller pillow, knowing Cakes would soon tire of the other pillow, which she did.
It's hard to explain "ownership" to my daughters. If they show me a toy and say "that's my (fill in the blank)" I usually have to say "yes, but it's a toy we share with our sisters." I know most siblings, multiples or not, go through this at some point. I just hope the concept of "yours, mine and ours" sinks in before they start trading black eyes.