When we create custom fields on the FAM Asset 'locked' custom record will those fields remain in the event of a managed bundle update? I was surprised we could create new fields but now I'm thinking if we have data in these fields it will be lost when NS does a bundle update.

I'm pretty sure it won't hurt them. I've definitely used custom fields on FAM before, though it's been years. IIRC you can manually update managed bundles in a Sandbox, so if you have a Sandbox that's old enough to not have the current version of FAM, you could add the custom field in Sandbox, then manually update the bundle to ensure it stays

Thanks. I’m looking through sandboxes now.

The updates won't impact custom fields