I think yu don't need any routing, just create the "A, "B" (and so on) ip users in the "22 ip endpoint licenses site", then logs in the same users (Hot desking feature) from any other site, the device will register locally "grabbing" the remote license. The only problem could be the both the incoming and outgoing call routing which have to be managed properly, there is a special feture in IPO which allows Hot Desking users to use LOCAL ARS, if I remember correctly.