What are brothers in Feng Shui?

I haven't heard of it, but I know that there is a so-called "trinity" and "six in one" in the theory of geomantic rationality. The so-called trinity and six-in-one refers to the attraction and cohesion of some forces in the five elements (wood, fire, earth, gold and water). Six in one is like a husband-and-wife relationship, and three in one is like a mother-child relationship. So harmony is the attraction, affinity and cohesion of the five elements.