Geographic coordinate system missing

Hello,

I'm currently working in a big railway project that uses a bespoke GCS.

I was following a forum post that explaining how to create a transformation. In the process the seed file "UserOverrideGeodeticTransformSeed.asc" needed to be altered.

The heading of the file contain the following text:

"# In case of absolute necessity it is possible to override the list or
# order of the grid shift files for a specific datum transformation.
# This should only be done if no other solution is available.
# Bentley Systems would be glad to introduce new files directly
# referenced by the built-in system dictionary as part of a refresh to
# its software. Contact Bentley system through the normal support channel."

As you can imagine this new GCS is a big headache with all the legacy data.

Is there anyone in the position to help?

Thank you in advance for your time.

Regards,

Eurico