At this point i just think that Gloriosa joined Rocks because she believed that with him she could meet Roger more often, because of the rivarly,and Shakky joined Hachinosu because she believed she would have attracted Rayleigh there in this way. Otherwise their actions dont make much sense.
By the way so Garling slept with a local God Valley woman during a mission,and impregnated her. Then he took Shamrock with him,some years later. Who knows whats the thing in God Valley that Imu would like,according to him!