Adding more aircraft to a 3rd party aircraft addon

I am trying to add five more aircraft to the recently released Airmicci MB339PAN (the Frecce Tricolori version) which is one of two versions included in the archive. This of course is a 3rd party addon, not an Official MSFS aircraft.
I am not experienced at all in adding liveries to an existing aircraft so am seeking help from those that know what they are doing.
This is my new livery