It was found that the synclinic interlayer interactions for materials having mesogenic cores made of repeating benzyloxycarbonyl units are stronger than for the parent MHPOBC and analogous compounds having biphenyl–phenyl mesogenic cores, as evidenced by significantly broader range of the synclinic phase and less frequent appearance of anticlinic phases in the homologous series. The biaxiality of the three-layer structure of the SmC*_Fi1 phase was directly observed at the temperature where the optical pitch is spontaneously unwound. The ferrielectric phase structure is nearly Ising-like. The Ising structure is most probably enforced by strong interlayer quadrupole order, in materials in which the ferri-phase appears nearly 20 K below the SmA phase.