Help overriding a single flag’s completion action

Guten Tag,

I’m trying to override the completion behavior for one specific flag of a
command, while leaving the rest of the command’s completions unchanged.

Environment: zsh 5.9 (macOS 15)

The completion file in question is:

https://github.com/danielmiessler/Fabric/blob/main/completions/_fabric

This file is automatically added to my FPATH when installed via Homebrew, and
the completion works as intended.

My goal is to override the values displayed for one option — the "--model"
flag — where I would like to provide my own values.

Currently, I copy the original completion file to my own completion folder and
manually edit the function responsible for the completion of the "--model" flag.
This approach works as expected.

Of course, I would like to avoid maintaining a copy of the original file and
instead override only the specific function used to generate the options that
can be passed to the --model flag.

Could you advise on the correct approach?