Deleted member 109224
The BBB could work, more seriously I could see them go to take Italy and be called the Latin Empire or Roman Empire if done before Napoleon.
Also every nation west of Russia just fainted.
I imagine that short of a total Franco-Spanish curb-stomping of the rest of Europe, a peace that allows for the merger of France and Spain would either involve promises to keep the Italian lands separate or the Bourbons outright losing the Italian lands (or part thereof).