This never moves the Children to where the parent(pivot) is.
It does. You're printing out the values of px, py, pz, which a) you shouldn't really do, you should use EntityX/Y/Z instead, and b) px, py, pz are the local positional values, meaning the children are positioned 0 units away fromt the parent.
Use EntityX/Y/Z(True) to get global co-ordinate values.