  Recently, a large number of protocols for bidirectional controlled state
teleportation (BCST) have been proposed using $n$-qubit entangled states
($n\in\{5,6,7\}$) as quantum channel. Here, we propose a general method of
selecting multi-qubit $(n>4)$ quantum channels suitable for BCST and show that
all the channels used in the existing protocols of BCST can be obtained using
the proposed method. Further, it is shown that the quantum channels used in the
existing protocols of BCST forms only a negligibly small subset of the set of
all the quantum channels that can be constructed using the proposed method to
implement BCST. It is also noted that all these quantum channels are also
suitable for controlled bidirectional remote state preparation (CBRSP).
Following the same logic, methods for selecting quantum channels for other
controlled quantum communication tasks, such as controlled bidirectional joint
remote state preparation (CJBRSP) and controlled quantum dialogue, are also
provided.
