Some websites use the same login for multiple domains (i.e. steampowered.com and steamcommunity.com), however it is not possible to have a single entry for both domains or link those entries so they stay synchronized when you change your password.
I would like to report the opposite idea: where I work I need access with different credentials to the same domain, but in different paths. For example: mywork.com/path_a and mywork.com/path_b So I would like the credentials to be associated not only with the domain but also with the page path. Also I would like the credentials to be associated with a title, so that if I need to use multiple credentials in the same place with the same username but different password I can do so.
I came here to suggest the same, the ability to link accounts from multiple websites so that when you change the password it changes for all of them.
In my work I have a lot of password entries for different subdomains of the same domain. Some of the subdomains use one account while the rest use a different account. Whenever one of the two passwords expires (and that happens often...) I need to manually check each of the password entries to find which of them use the password I just changed in order to update the stored password.