These bodies are not separate. I consider them "nodes" or octaves on a continuum. This continuum consists of the primal "substance" of existence, which is self-radiant awareness, which gives rise to "soma" (or "living, aware, psycho-physical person"); soma consists of these three "bodies" or nodes.
Of these three "bodies", two are manifest (limited and defined), consist of changing processes, and exist in time: the Nirmanakaya (genetic body) and the Sambhogakaya (dream body). These two bodies are not static and unchanging, but exist as living, changing processes.
The third "body," the Dharmakaya, is transcendental, all-pervading, and is the ground of being from which the other two arise and in which they exist, consisting of self-radiant awareness.
This writing describes and explains the interrelation of the three bodies in terms of personal/conscious evolution.
People who are just learning the process of deliberate growth and change, we call "proto-mutants"; people who are actively engaging deliberate growth and change, we call "mutants" -- after Thomas Hanna's usage in his book, "Bodies in Revolt".
"Pointing Out" Instructions
When the Nirmanakaya (manifested genetic/memory body) and the Sambhogakaya (imaginary dreamed-body) align (or attain a high degree of mutual congruency), as the individual remains consciously awake, volitionally present and at a sufficiently poised state of equanimity or balance (free attention), the Dharmakaya (deep, silent, formless body or field) may be intuited by feeling the content of experience and, while feeling it, feeling beyond it into what is deeper.
By "a high degree of mutual congruency", I mean that the genetic/memory body is sufficiently free of the grip, or "gravitational attraction" of habituated patterns to be able to transform freely and stably into new subtle perceptions captured by awareness in the dream/imagination body (Sambhogakaya). Otherwise, subtle perceptions are fleeting and quickly replaced by the habits of dense memory seated in the genetic/memory body (Nirmanakaya). They can't be captured, so subtle perceptions, new insights, and emerging abilities vanish and get missed.
The Dharmakaya is the "clutch pedal". As the formless aspect of buddha-nature, "resorting" to it (or "taking refuge" in it) is the means of disengagement from, or relinquishment of, the memory-form of the moment. Dynamic balance between the intuition of the Dharmakaya and intuition of the form and feeling of the Sambhogakaya (imaginary dreamed-body) allows the Sambhogakaya to transform. Without that dynamic balance, the Sambhogakaya remains bogged in its current form, anchored by the Nirmanakaya's tangible memory pattern (present as physiological adaptation, neurological conditioning, and the patterning of the myofascia/soft-tissue), which feeds back the memory pattern to the Sambhogakaya in a self-perpetuating feedback loop. You can't lift the foot you are standing on; you're using it.
The Nirmanakaya/genetic body is the densest seat of memory and is slower to (and more resistant to) change than the Sambhogakaya (dream-body), and so introduces a lag into the process of change -- which has survival value, but slows re-adaptation.
The "anchoring" of the Nirmanakaya is its habitual pattern; intuition of the Dharmakaya "lifts anchor".
Ordinarily, the perception of the Nirmanakaya/Sambhogakaya dynamic fades in deep sleep, leaving only the Dharmakaya's formless nature. This is rest. Upon passage from the deep sleep state (Dharmakaya) into the dream state (Sambhogakaya), residual memories imprinted upon the Nirmanakaya (daytime body) "leak" into the emerging dream-activity of the Samghogakaya. Dreams appear, whose elements are, every one, aspects of the dreaming individual.
The "Ins" and "Outs" of the Subtle/Dream Body (Sambhogakaya)
Though it has been said that dreams are the royal road to the Unconscious, it is better said that they are the royal road to pervading the Unconscious with Consciousness. It is fruitless and misguided to consult "dream interpretation" texts for their meaning. They are indirect, second-hand, and intellectually biased, if not outright arbitrary.
There is a better way: Merely to remember each element of the dream and notice what you feel as you put your full attention on each element -- that action reveals the latent significance of the element attended to. It's a "feel" thing. The feelings are likely to be very familiar. More than that, with recognition comes dissolution of the binding forces of those feelings.
With each recognition and dissolution come both greater access to intuition of the Dharmakaya and release of the physical form (Nirmanakaya) from hitherto unconscious patterns of contraction (or somatic/psychophysical shaping forces). The body changes.
As the process of recognition and release continues, there appears a feeling of "straightening out". The process gives meaning to a term that Castaneda used, "The Mold of Man". (I think it was in "The Fire from Within"). The "straightening out" progressively approximates a feeling of more natural wholeness, of "self as you would prefer to be", which is The Mold of Man.
The process of that straightening out may involve passages through personal distortions, recognized as "damaged self", dysfunctional patterns or neuroses, some of which may be pretty hairy. It gives meaning to the term, "Lions at the Gate" or "Personal Demons" or "The Dragon's Lair" or "The Green Knight" (but not The Jolly Green Giant).
As it proceeds, the energy-dynamic of the individual changes -- not wholesale and in some general fashion, but in specific ways energetically/vibrationally related to the material recognized and released. A person gets more spontaneously intelligent in various ways.
The Special Function of the Formless or Most Subtle Body (Dharmakaya)
However, without the balancing influence of intuition of the Dharmakaya, transformation is slowed, rather than allowed -- hence the value of meditation -- and of a good night's sleep! Paradoxically, as the process proceeds, the person may find (s)he needs less sleep and spontaneously spends more time in early-morning meditation. Or maybe it's just insomnia. But you can put the time to good use!
Now, as the energy-dynamic of the individual changes, the field of the individual tends to become quieter -- that is, less beset by occlusive noise -- more "resonant" to processes occurring within and outside. The faculty of intuition becomes more available. With less internal noise, the individual is more sensitive -- particularly to subtle forces guiding and shaping the emergence of actual existence. In other words, the person may become spontaneously pre-cognitive, getting intimations of things to come through revery and streams of thought. When those things come to pass, people call it, "synchronicity" or "signs of wisdom".
It's a natural result of doing "clean-up" which, by releasing the "glue" of memory patterns, allows the Nirmanakaya to change more quickly/fluidly, and the energy dynamic of Nirmanakaya and Sambhogakaya to be more congruent. (The physiologically-based memory-"glue" of the Nirmanakaya makes it slower to change, and so less dynamic than the dream-body/ Sambhogakaya. They get out of phase, as attention is trapped in memory. Somatic education helps in the releasing of that "glue".) As Nirmanakaya and Sambhogakaya become more synchronous and congruent, they seem more transparent and attention is more free to penetrate to the deeper layer or node of consciousness: the Dharmakaya.
As both Sambhogakaya and Dharmakaya are simultaneously intuited, spontaneous adjustments in the field of the Sahbhogakaya (dream body) occur in the direction of felt balance and centered wholeness (these words being metaphors for a felt experience), these being how the Dharmakaya manifests through or as the Sambhogakaya. The Nirmanakaya undergoes corresponding evolutionary mutations (at a personal, not species, level).
This simultaneous intuition may be fostered by the presence of persons or objects imprinted with the harmonic of "Nirmanakaya/Sambhogakaya Manifesting Dharmakaya". Such is the virtue of spiritual masters, the localities of such masters, and the relics of such masters, of teachings generated from such intuition, and of groups of practitioners.
What may start out as an idealized state in certain aspects of the individual's make-up broadens to include more of the individual's functions, with consciousness of the Dharmakaya progressively pervading the dream-body and its manifested-memory (neural/genetic) body, to the benefit of ongoing mutation or "personal evolution".