Sorry this comment comes a bit late, but just to point out that you don't need an additional level and the cost that incurs. All you need is an inner and an outer corridor on the arrivals level. The outer one, by the windows, could be for domestic arrivals and lead to the left (towards gate 1), behind that, leading to the right and connecting to the international arrivals side, is your corridor for international arriving pax.

You configure it so that usually, all the jetties feed into the domestic corridor. But on the rare occasion you get an international arrival there, you open the doors to allow that jetty to lead to the international corridor, and you simultaneously shut doors to block off the domestic corridor on either side of that stream of passengers. On the rare occasion that you have a domestic arrival at the same as, and at a higher gate than, the international arrival, all it requires is one staff member to be stationed at the junction and every couple of minutes he stops one group and switches the doors, like traffic lights at a junction.

Cost? An extra glass partition to create the second corridor, plus 6 or 7 gates' worth of doors. But you'd save the coaching cost and, more importantly, an awful lot of passenger, crew and aircraft time...