serious problem with liveries outside pmdg

Future Airline Pilot Hey guys and girls, Can someone help me with the non pmdg paints. I figured out that you have to copy and paste the texure.someting file into the PMDG texture file. And it works, but as soon as i try to change that file back to a texture.something file it dissapears. So does this mean i can only have one repaint? Please reply. Thanks. Scott