I love imadeltaz's sweatshirt idea!
I wish I had started that with my little, but unfortunately we aren't close (I'm a co-big with another girl). It's sort of like passing down shirts and stuff...I've heard of other chapters doing that.
Maybe, if people are wanting to keep the shirts instead of handing them down, each subsequent big might give her little a shirt of her very own with all the names down the sleeve...just a thought. It would probably be expensive, but that way she could keep it forever and maybe add names to it herself as the tree grew.
By the way, why did they kill all your trees?? That sounds slightly unsisterly.