Worth while to get that done on your next visit there. I was able to do most of my stuff stateside at the Thailand embassy in LA to make the process easier in Thailand. Sure it's similar in France. You want to get your marriage registered there because it allows you to open bank accounts, get drivers license, and basically be able to apply for citizenship there if you ever wanted down the line. I fly out to Thailand late November and plan on getting my citizenship finalized while there. My wife who came on a K1 also got her citizenship this past April. As others have said, do the SS office the day she arrives. I arrived in LA on a Sunday night late and drove back to Vegas. Dragged the wife to the SS office at 9am the next morning and applied for her SS card. 13 hours after landing in the US. Don't let the office give you any pushback saying you have to wait a few weeks before you can apply. The Computer updates the moment they enter on their K1 now, 10 years ago you used to have to wait 2 weeks, not anymore. Make sure if they say come back, politely ask them to check the computer, information is there, just government employees tend to like to kick the can down the road whenever they can. Good luck on your journey, I remember when I was in the same place you are. it's going to take some serious patience and studying to get thru it, but it is soooooo worth it in the end.