Let's try a different approach.
I have soulmeld shaped, lets say Vitality Belt. I am level six so it has a capacity of two essentia. I have two essentia invested into it, gaining its normal benefits, 2*meldshaper level in hit points.
A.
I use Psycarnum Infusion, making Vitality Belt treated as if it had its full capacity, regardless of how many essentia is actually in it. Now I reinvest all the essentia from Vitality Belt into another incarnum receptacle(s). Vitality Belt is still giving me 2*meldshaper level in hit points.
B.
After reinvesting, but still in the same round, a random caster uses Divest Essentia, all my incarnum receptacle(s) lose their invested essentia in them, but Vitality Belt is still giving me 2*meldshaper level in hit points. Otherwise I would have just gained bonus essentia.
C.
Later a caster casts Essentia Lock on me, I have not reinvested into Vitality Belt, I use Psycarnum Infusion, making Vitality Belt treated as if it had its full capacity, I gain 2*meldshaper level in hit points.
D. (the example that assumes there is actual investment, so there is real essentia)
I use Psycarnum Infusion, making Vitality Belt treated as if it had its full capacity until the beginning of my next turn. I now reinvest the two essentia from Psycarnum Infusion into another incarnum receptacle(s). Vitality Belt is still treated as if it had its full capacity until the beginning of my next turn, but which essentia do I lose when my turn begins, the feat mentions only essentia in the incarnum receptacle you used it on? Would this allow for infinite essentia?