Given that Dhanbad Division single-handedly contributes 95% of ECR's earnings, I don't think they will ever let their golden goose elsewhere!
And making a Jharkhand state centric railway zone without Dhanbad division would be foolish imo considering how Dhanbad essentially encompasses the majority of railway territory in Jharkhand. Ranchi, Asansol and Adra are all in minority, and DDU, MLDT & HWH divisions have marginal presence here...

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is in my opinion that for the sake of all aggreived parties it is better to split up Dhanbad Division which covers a large territory...

1. Manpur-Pradhankunta stretch can go back into ASN Division and DHN ceases to be a division and gets shifted to ER along with Giridih branch lines.
2. MESR-BRKA-CPU and GHD-DOS sections, can be made a new division and moved into SER with BRKA as divisional HQs
3. CPU-SGRL can be moved in WCR JBP Division...
4. BKSC gets moved into RNC dIvision, ADRA-BQA-MDN is merged with KGP.
5. ANR-CNI stretch is moved in with CKP divisions...

I believe this would solve up a lot of impending issues, new zone may-not be actually needed. ECR would end up losing a lot here but I am no sympathies towards them so I couldn't care less!