I had a problem (v7complete) that when I populate from the bottom up, populating the upper layer emptied the lower layer. This cant be right particularly  if you have affinities between the ecos in the different layers. You must populate the upper layer last.
But in principle, It really shouldnt matter in which order you populate. Quite often I change my mind about the details of the various ecos. If I repopulate one layer I shouldnt need to repopulate any of the others, some of them are time consuming.

"I paint that which comes from the imagination or from dreams, or from an unconscious drive. I photograph the things that I do not wish to paint, the things which already have an existence."
Man Ray, modernist painter
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