Is it possible to overwrite custom fields from an unlocked package

Question

I am creating an unlocked package from a separate Developer edition. In a sandbox we are adding custom fields which at first are not clear if they have to be added to the package to gain speed. Is it possible at a later moment to add these to the unlocked package and overwrite the custom fields in the sandbox with the unlocked package for testing and when ready promote the unlocked package with all needed custom fields to production.

If this is not possible because of a custom field being a different field with a prefix. What would be a working solution to be able to create the unlocked package while not stopping the proces of being able to create custom fields in sandbox.

Thanks in advance

Answer 1

You can add the field to the Unlocked Package later, and when you install the new package version with the field included, it will indeed be overwritten by the contents of the package. This design is what allows developers to migrate their existing org metadata into packages over time. You simply need to add the field's metadata to your repository, then build a new package version.