Target only Basic Authentication

Hi

Is there a way to create a login that would only be used for Basic Authentication ?
We have pages that require Basic Auth, then there is a web login page, for which I want to store several accounts.
If there were only 1 web account, I could store in custom fields, entering the name of the form fields in the same entry as the Basic Auth one. But since I have multiple accounts for the web part, I don’t know how to do this…

Thanks

Émilise