There are people that change planes in Geneva from somewhere to France, and they all have to go through the same security check in the French sector. That security checkpoint is one of the same for people originating in Geneva and those coming from another flight. Therefore, I would assume that they do accept sealed duty-free bags.

I also believe that it shouldn't be a problem for you to get the sealed duty-free bags when buying your bottles. When being asked for your boarding pass, you would only show the next leg, which in your case is Geneva, but then typically passengers are being asked whether they have an onward connection and would require a sealed duty-free bag. you may just say yes.

Just one difference between domestic to domestic and domestic to international: Switzerland not being part of the EU means that there are some more active customs officials at the point where you cross from the Swiss to the French sector of the airport. If you stay within the French sector, he would not pass by those customs officials, Who might indeed ask you questions.

One question though: I may have misread it but you are asking for transfers within the French sector, but then later on say that you're arriving with the bottles from the UK? Or do you actually fly from the UK to Paris, then onward on Air France to Geneva?