Géry Van Troyen

Hi there, as a newbie I hope this is the right place to put my question. I recently bought True Earth N-C-S (a must have !!) and London City EGLC which to my surprise had the old layout (X-plane 12 has the new layout). So I was a bit disappointed and I wonder if I can edit the layout and add the extended apron and taxiway in some way. Am I allowed to do so? Is there someone who already did this? Some tips? Thanks