It also means, where only one person is a company, the other person has such an interest that would make it the holding company (if it were itself a company).
Mae hefyd yn golygu, pan mai dim ond un person sy’n gwmni, bod gan y person arall fuddiant o’r fath a fyddai’n ei wneud yn gwmni daliannol (os oedd yn gwmni ei hun).