[chzvacmyye]

This collection of bodies refers to the body parts, like hands, head, foot, etc., and among others, breathing?

hi KA

no

the physical body "collection" is simply the physical body the mind can feel/sense at the same time as it feels/senses the breathing

for example, the breathing suddenly becomes very relaxed and then, at the exact same time, you feel your body becoming very relaxed

this is experience "all bodies" or "both bodies"

the mind experiences the comfort/discomfort of the physical body that occurs with the different qualities of the breathing

it is to experience a cause & effect relationship between the physical body & the breath

as for the preliminary steps of Anapanasati, they are:

1. experiencing when the breathing is long
2. experiencing when the breathing is short
3. experiencing the cause & effect relationship between the body & breathing ("all bodies")
4. experiencing the calming of the breathing

kind regards