I experience another problem with copy_particles procedure.
It seems to me, that if I copy a big structure with bonds between internal particles, the second molecule's particles won't have numbers "as originals + constant shift". Perhaps it happens when I copy set of particles once, then add some new particles, bond them and finally copy all the range once again. In all examples I experienced this problem, there were branched structures, where I mixed numbers, but they are not matches respectively anyway.
I need numbers, for example, if there are few branches from one point and I have to know what are the id's of particles closest to the core particle and what are the id's of next level, so that I could use angle bonds after creating them. Here is a simple sample (sorry, it's not really good). As you can see, particles with different types should be at the same positions.