My chapter went through the alphabet, and then began designating new member classes as our International organization designates chapters...so the first chapter after Omega was Delta Alpha....after Delta Omega, we would have Phi Alpha....after Phi Omega, we would have Epsilon Alpha...after Epsilon Omega, we would start then at Alpha and skip the Delta Phi and Epsilon during the rest of the alphabet.
Makes sense
They just had their Delta Eta class I think.