Western line isn't connected with central line. For traveling to bct the train will have to be taken via udn.
Btw why do you want a train for bct from hwh?
A train from every station of a city to every other station of another city will pose nothing but operational constraints for ir. For people residing in bct and churchgate area local transport is the means to reach cst. Ir cannot be made to suffer for the responsibilities of local authorities.