Multiple systems in a single simulation

I am simulating cacao butter which contain 3 triglyceride with different proportion (POS 48%, SOS 34%, POP 18%)
Can you please tell me if there is any command which can do this

This is not a question that can be handled with a LAMMPS command. LAMMPS does not care what you are simulating. It just looks at your positions, your topology, your choice of styles and then computes the forces and applies time integration.

How you build your system is a different task and one that is usually performed outside of LAMMPS.
Please see, for example: Pre/Post Processing Tools for use with LAMMPS

thank you for your help
but in this list i found a lot of software tools
can you please tell me which one of this software tools can I use in my simulation

Can you first please tell us how much pre-existing experience you have with MD simulations and particularly with LAMMPS, what your research background is, and what you want to learn from your simulations?

I’m phd student
I don’t have a long experience with LAMMPS, but in my simulation I am trying to find results found experimentally using LAMMPS.
In this article you can find experimental results
Comparative structural and vibrational investigations between cocoa butter (CB) and cocoa butter equivalent (CBE) by ESI/MALDI-HRMS, XRD, DSC, MIR and Raman spectroscopy*.*** Food Chemistry, Volume 363, 30 November 2021, 130319

I want to know if VMD is a good choice

A good choice to do what? VMD can do many things.

It looks like the biggest challenge for you is that you are lacking experience in setting up simulations for molecular systems in general. That requires some tutoring and reading of text books and practicing with simpler examples than your research project. Also you should look up publications that did something similar to what you want to do. Running a simulation and then expecting it to reproduce experimental data is not as simple as your statements are implying. However, this is not something that depends on which tools you use, but rather on having a tutor that will guide you to the process of setting up systems with a suitable force field, validate them and how to design simulations to extract useful information from them. The actually running of the simulation is usually the lest difficult and least interesting part, the planning and analysis are what matters the most. Unfortunately, this is not easily learned from a forum or from using the “right software”.