This is a useful feature that LastPass has. this would prevent from creating multiple duplicate entries in Edge password manager and also manage logins more efficiently.
in LastPass it's called Equivalent domains, the description says:
"Add domains that use the same login service. We've already listed popular sites that use shared credentials across domains under their control. For example: amazon.com and its local variations, or gmail.com and other google products."
it's pretty clear, instead of saving 2 password entries for Facebook.com and Messenger.com , we use the same set of username and password for both websites. this also makes it easy when user changes password for one website, because the other one will be updated automatically.
It's not hard to see how bundling these domains together and allowing saving of one username-password for all would be beneficial.
As it stands today, Microsoft Edge (and other Chromium browsers as well, but not 100% sure about all) classify passwords at the domain level. This works quite well for most use cases, but not in some special cases.
the good idea is (at least for now) warn us (with the news security feature if leak) if we have the same password multiple time, and have a button to ignore it with (same account option) or something like that. With that we can have an additional security who prevent reused password and it will help you to create slowly a database of domaine who share username/password (if you implement that later).
Currently, even if the same username-password is reused on multiple sites they ALL get flagged in the alert as being at-risk. There is no common re-use warning for this scenario.
Password reuse is a common problem, but it can happen between both related and unrelated domains.
