As you aware that FCRA department has made DARPAN ID compulsory for all FCRA related services since October 2017. Since then, for every service of FCRA, like filling Annual Return, Updating quarterly receipts, FC registration, renewal etc.. website prompt you to link DARPAN ID of your organisation.
However, there were lots of technical difficulties in generating DARPAN ID with darpan ngo website. Those who got the DARPAN ID before 2017 could not link it with FCRA department. Also, technical queries were not answered promptly by the department.
Looking to all such difficulties, FCRA department has reconsider it and now made it OPTIONAL to quote DARPAN ID with FCRA portal. Read the full notification here. This is a welcoming step from FCRA department.
If you have already generated DARPAN ID, it is highly advisable to link it with your FCRA registration.