about extracting molecules

Dear Lammps Users

I am generating a structure which contains (water, hydrogen, oxygen, and nanoparticle)
the system after some time will generate a new type of molecules I have to dump the coordinates of the atoms
and I can count the number of molecules using such command “fix new_mol all reax/c/species … etc”
and it gives me how many specific molecules the system has.

But I am not able to extract the molecules coordinates only, is there any postprocessing tools I may use
to only extract the molecules which formed?
I have initiated the bonds for those atoms but I still can’t reach the right way to get those molecules properly as I am
looking to check all molecules evolution over the time frame,

Looking at your advice and opinion

Thank you