Why would the Austrians give it the their French allies? Would they receive some other territory in exchange?
Actually France will obtain all of the Austrian Netherlands...its part of their agreement with the Austrians of 1757. Austria obtains Parma instead and an annual subsidy from France (6 figures I think it is) Until Silesia is obtained from Prussia.
So if Prussia is out.. France with What is essentially Belgium is not something Britain is going to favour but they will be powerless to prevent it...but it also gives the French even more bargaining room where Britain is concerned once they also obtain Hannover. I am still of the opinion that Britain would trade their gains back for the Historical domains of George III it is the whole rational for the Prussian alliance after all.
So lets say '62 Britain still puts the pressure on for Prussia to make concessions and obtain a general peace or face the loss of its subsidy from Britain.. I can hardly see Frederick making concessions if Britain is unwilling to either so the general feeling must be that they can obtain some Status quo ante bellum at the very least with any gains by their opponents coming from Prussia. This was the Experience of Maria-Theresa in the previous conflict so its not out of the question.
At this point I cannot see Maria- Theresa settling for anything less than the entirety of Silesia. Russia will also have to have its pound of flesh ( Ducal Prussia) to trade to Poland for Courland If the Austrians and Russians continue to press Frederick, he's down to only 60'000 troops they are likely to prevail or force the issue on their own terms by years end in anycase. If Britain ceases its subsidy, Frederick simply tumbles faster.
OTL Elizabeth died giving Frederick a much needed reprieve from the Russians and the Swedes ( Russian negotiated truce there). Here he will likely remain pressed by all 4 to the end.
Sweden will end up with its losses in Pomerania restored or an indemnity. Russian, Austrian and French gains have been discussed that leaves Branden burg with its core and East Pomerania with Saxony perhaps picking up Cleves, Mark and Ravensbruck. East Friesland I am not sure of as its abit far off for any of them but perhaps Russia or Sweden and then traded to Denmark or Oldenburg for something else.
That leaves Britain... I still lean to the status quo ante bellum as it is the pattern of previous conflicts where the British alliance has come out on the back end of things.
There is much on the continent that Britain will want to ameliorate as much as possible even though they have done significantly better in the colonies...its still Europe that counts and the balance of power there that counts.