Combining two data files

Dear LAMMPS Users,

I have two LAMMPS data files from two simulations, both of different box sizes and forcefields and I want to combine them into one. Can anyone recommend a good way to do this. I figured copy and paste could do this, but that may be too error-prone. Has anyone done this? How does one take care of overlaps, atom ID, and molecule ID? Is there a program or script for this?

Thank you very much.

you can use the read_data command multiple times in an input script. you should check the docs for the details

Thank you very much Jacob.