Specify multiple upstreams

[ComradeVanti]

Hey there. I've looked the documentation up and wanted to ask if the following is possible:

I want to install Package A from a private GitLab registry. I have setup the authentication, all is well. I specify the registry using the --registry option. The package is found.

Package A has a few dependencies. First Package B. This package is a official Unity package and so is found in the upstream. No problem. But Package A also depends on Package C which lives on OpenUpm. This fails because, to my understanding, if you specify a registry option, the given registry will replace the OpenUPM registry. Is this correct?

Would it instead be possible to prepend the registry given by --registry to the list of registries to search? So first search the custom registry, then OpenUPM and finally Unity.

I have a related question about if it would then be possible to store this custom registry in a config file somewhere so I don't have to add it every time.

I am open to attempting to introduce this change myself, I just wanted to ask first if this is already possible and I just missed it. Thanks :)