I prefer to break up LR with the zoos still attached.
If this isnt possible....
Zoos are attached to LR and eachother via a "mat". Often times the "mat" can be slowly removed or peeled from the LR, and superglued on to a piece of LR. When using superglue, make sure it's "Superglue Gel", which I find at my local grocery for about $2.50 per tube. Just have a piece of rubble ready, dry the rubble off, and put a couple of dabs of superglue gel where you want the frag. Then place the frag on the glue, and hold it there for a minute or two. All done.