Hunger Games-"Catching Fire" Connection

When Katniss visited the woods one day, she met two girls from District 8 that escaped and came to District 12 preparing to put their plan in action. The one was Twill and the other was Bonnie. They escaped their District because they decided they wanted to start a rebellion and take revenge from the Capitol. They found the opportunity when the whole district started the uprisings and the Peacekeepers were busy with other people and escaped. They think that District 13 has alive people living in it. They say that the Capitol has been using the same footage over and over again when saying something about District 13 because there's a mockinjay that is showing in the background and does the same thing always. They also think that the people moved underground when everything on the surface was destroyed and they managed to survive since their industry was based on nuclear development ( they were graphite miners). They told Katniss that they would go and visit the place to find out the situation and asked her to go with them. In my opinion the girls are right because there HAS to be something left going on there after 75 years. They should go and find out what's going on and maybe if it's safe, Katniss, Gale, Peeta, Haymitch and their families could go live there for the rest of their lives. It;s also logical because the people were coal miners. They could have survived and now they are living underground. The Capitol doesn't know that because they think they destroyed everything and everyone but what if they are wrong? What if there ARE people living underground of District 13 and nobody knows about them? But the only problem is how do they reach District 13 and what if there are cameras or security there? The only way to find out is for the girls and Katniss to go and visit the place and see for themselves.