I think it would be easier to think about it the following way.
1. Nāmaloka (viññāṇa dhātu) consists of the four mental aggregates: vedanakkhandha, saññākkhandha, saṅkhārakkhandha, and viññāṇakkhandha.
– Part of it (associated with kamma viññāṇa) is “energized.” It has kammic energies created by kamma viññāṇa.
– The rest has no associated energy; those are only memory records.
– Now, we also need to realize that “memory records with kammic energy” keep losing kammic energy with time and get added to the part without energy.
2. In that sense, the two categories do not stay separated. There are two categories, but the “energized nāmagotta” keeps moving into the other category over time.
– But more “energized nāmagotta” are being created as one cultivates abhisankhara.
– Of course, even more “non-energized nāmagotta” are also being created as we live our lives. Each experience is added to nāmagotta.