Highly first order silane end-group difluoroterphenyl liquid crystal was added to trifluoroterphenyl host with a nematic to smectic-C phase transition to increase its first order nature, achieve a higher cone angle and reduce its temperature dependence. Increasing concentration of the additive, caused a linear decrease and eventual disappearance of the nematic phase. A smectic-A phase was injected at 35% concentration, making the transition second order. Optical studies of the mixtures showed little dependence of the highest value of cone angle on concentration. The original host showed first order cone angle behavior and was used to fabricate a twisted FLC device.