I thought this would be easy but it’s not working. I created a 50×50 stickfigure shape C and placed it in a 200×200 comp B at the top. Then i place comp B 6x in a 200×200 comp A and rotated each +60 degrees. So you get this http://www.patrickjansen.net/AE/tmp.html
but instead of having each stickfigure rotated according to the manual rotation, I tried rotating them “back” (so they’re all upright) by attempting to read in that manual rotation -> (in the subclip B rotating it “back”) by setting C rotation value to expression -thisComp.rotation but it’s not working. Result should be like this but isn't http://www.patrickjansen.net/AE/tmp2.html
I'm not sure exactly what you're trying to do but if you want the value you enter in the rotation property to carry into the expression then just put "value+" at the beginning of the expression. Another thing that might be throwing a wrench in the works is that your expression is for the comp, not the layer, which may be a problem but it's hard to say since your goal is unclear.
That will only work if each comp B was created by duplicating the comp (in the project bin), not the comp B layer in comp A. Each comp B needs a unique name (like "comp B1", "comp B2", etc.). Then you could do it with an expression like this: