Blendmode ignored

good evening

i am trying to to assign a blendmode to children of some movie clip (“smc”).
if i set the blendmode of smc to, say, overlay, everything works, all the children are nicely overlayed, etc.

if i set the blendmode to the children, leaving smc “normal” - nothing.
i have played around and it appears that since there is nothing behind those children inside smc, it considers their own personal background white, and their blendmode becomes meaningless.

is there any way around it?
any way for children to notice their actual, visually speaking, background?

many thanks and wonderful day,