From my point of view Subarnarekha should take the shortest path but it's also create a void of connection between dhn adra. After the bankura dhn memu there is no other train left for dhn. If SER or ECR arrange some alternate memu connection ( I 'm also sure that they won't bother about the passengers and new services) then we can consider the re routing of subarnekha. Let's see what happens.