Combine some topologies

GROMACS version: 2019.4
GROMACS modification: No


I have parameters of a pegylated GOLD nanoparticle that is provided by the NanoModeler tutorial (with their respective .itp and .top)
And also, I have a balanced membrane (8 us of simulation) of POPC type (from CHARMM-GUI/Martini Maker server).
Now I want to mix and simulate the NP on the whole membrane. He used various ways to mix the topologies (both for martini 2.2) and got no results, before showing my pipeline I would like to know any recommendations or if there is any correct way to do this combination of systems for the simulations.