I don't think that you should be classifying something as exclusively one particular aggregate. Khandas are not "things". http://what-buddha-said.net/library/Bud ... tm#khandha
Some writers on Buddhism who have not understood that the five khandha are just classificatory groupings, have conceived them as compact entities 'heaps', 'bundles', while actually, as stated above, the groups never exist as such, i.e. they never occur in a simultaneous totality of all their constituents. Also those single constituents of a group which are present in any given body-and-mind process, are of an evanescent nature, and so also their varying combinations. Feeling, perception and mental constructions are only different aspects and functions of a single unit of consciousness. They are to consciousness what redness, softness, sweetness, etc. are to an apple and have as little separate existence as those qualities.
While I do agree substantially with the above, I think it is only generally true that the experience cannot be pried apart at the triad of feeling, perception and consciousness: MN 43 which suggests that all 3 are saṃsaṭṭhā
(conjoined) and not otherwise.
The bit about the qualitative aspect of the experience (softness etc) might be furnished by rūpa
as an Aggregate (minus the formless states), but is saṅkhāra
conjoined to each experience?
AN 4.235 suggests that saṅkhāra
is optional. In each of the cases where there is dark kamma, bright kamma or dark-&-bright kamma, the sutta says that the person "fabricates/generates a bodily/verbal/mental fabrication" accordingly (ekacco sabyāpajjhaṃ kāyasaṅkhāraṃ abhisaṅkharoti, sabyāpajjhaṃ vacīsaṅkhāraṃ abhisaṅkharoti, sabyāpajjhaṃ manosaṅkhāraṃ abhisaṅkharoti
is a common synonym for the verb of saṅkhāra
Yet, in the 4th case of kamma that is neither dark-nor-bright, the XYZsaṅkhāraṃ abhisaṅkharoti
possibility drops out of the picture. Apparently the kamma that ends kamma is somewhat special, where saṅkhāra
does not necessarily intrude.
All very mysterious. Perhaps there is a slight difference in emphasis on what saṅkhāra
means in DO as against the Five Aggregates model.