3 are simply different aspects of forms

These 3 are simply different aspects of forms. Each kaya has 3 different facets. For example, the dharmakaya of dharmakaya is Buddha Samantabhadra; the sambhogakaya of dharmakaya is Vajradhara; the nirmanakayas of dharmakaya are the 5 lords of the buddha-families. So, Amitabha, as head of the Lotus family, is classified here as nirmanakaya. The dharmakaya of sambhogakaya is Vajradhara; the sambhogakaya of sambhogakaya is Vairochana Gangchentso; the nirmanakaya of sambhogakaya is Sakyamuni Buddha. The dharmakaya of nirmanakaya is Amitabha; the sambhogakaya of nirmanakaya is Chenrezig; the nirmanakaya of nirmanakaya is Guru Rinpoche. So, here, Amitabha is the dharmakaya.