Two questions, one reply.
Quick question, will it damage the jacket if you replace a patch that has already been sewn on?
Yes. Simply put, leather material is not forgiving at all. This is why most folks put on their nametag, and that's it. When you sew on a patch, the needle punches the leather and if you ever take off what is on there, you better have a patch that will cover it exactly. Those holes stay there and don't close up. The CWU-36/P and CWU-45/P (summer and winter weight flight jackets) are made of aramid cloth, so when the needle goes through, it simply pushes the threads aside. So when you take off a patch there... a little heat or steam and you'll never know anything had ever been there. This is also why if you ever have any repairs needed to a leather jacket, don't take it to the PRAN in the shop. Talk with the PR1 to find out who is the best at sewing in the shop. Once you mention it's for a leather, most likely, he'll be the one to do it and not the junior guys.
I got a new pack and wanted to patch the US flag on there to show some pride.
Pride at home is one thing, and I'm all for it. However, pride abroad has the strong potential to make you a target. Movie references aside I think that the history of this young man could drive home my point better than anyone.
http://en.wikipedia.org/wiki/Robert_Stethem
Key notes:
When their demands were not met, Stethem was singled out. The hijackers learned he was a member of the U.S. military and then beaten and tortured. Finally, the hijackers shot him and dumped his body onto the tarmac at the Beirut airport.
And from the State Department website:
TWA Hijacking, June 14, 1985: A Trans-World Airlines flight was hijacked en route to Rome from Athens by two Lebanese Hizballah terrorists and forced to fly to Beirut. The eight crew members and 145 passengers were held for seventeen days, during which one American hostage, a U.S. Navy sailor, was murdered.
You'll notice that only 1 of 153 was murdered.
Just .02 from the paranoid guy with a little salt behind the ears.