The essential idea of the liturgy of Ushpizin is to invoke the energies of the seven lower Sefirot in the proper order, so that Shefa, blessing and sustenance, can be drawn down into the world. This is the essence of Kabbalistic liturgy, and a liturgy of the imahot would only make sense if it were to follow that pattern. That means we have the playfully serious task of finding a stable order for the imahot where no clear order exists.