Serverless Deploy Add/Remove API Mapping from Custom Domain

New here and getting started with Serverless. I have my stacks running correctly, now running into an issue with my custom domains.

I have the custom domains pre-configured in my API Gateway, but I also need to add and remove the API Mappings for those custom domains and I am not seeing anything readily available to do this. Any suggestions?

I have found this:

  - serverless-domain-manager

    basePath: hello

And wondering if this is what I need to do since I already have a constructed custom domain. but when looking at the console to add the API mapping, you need the API, Stage, Path…so not sure if those are just entries in the customDomain section?

Thanks for the help!