Our earlier model of liquid crystals consisting of highly polar compounds in which the molecules can form either parallel or antiparallel pairs, has been extended. Depending on the model parameters the following results are obtained: (i) first order SmA-SmA which changes over to a continuous SmA-SmA regimes of the McMillan alpha parameter, (ii) a re-entrant nematic lake associated with the SmA-SmA boundary, and (iii) the merger of the re-entrant nematic lake with the nematic 1 d sea. The results are discussed in comparison with experiments and other theoretical models. transition 1 d evolution beyond a critical point in two 1 d