The influence of the "read_data" command on the "rerun" calculation

Hello all! I use the rerun command to calculate the force between atoms. Since the parameters such as bond interaction cannot be obtained by the rerun dump, I use “read_ data” command. The system is a two-dimensional periodic boundary, and the z direction is non periodic.
I want to know if I use “read_data” for two different files, only the number of water molecules is different in the two data files, the other parameters such as bond and angle parameters are the same, and the dump file of “rerun dump” is also the same. Are the forces obtained in these two cases the same?
According to my understanding, as long as the “rerun dump” file is the same, independent of the number of atoms in the “read_data” read file, but the force I get in these two cases is different, I don’t know why.

No. You have two different systems with different topologies and different number of atoms.

You need to update your understanding.