This is more of an enhancement request which the support team seem unable to accept and redirected me here.
The concept is simple and seems to address several other threads on subdomains for Identity Safe (IS).
In the IS config window, there are currently 3 checkbox options. Require Vault Password; Auto-fill; and Auto-Submit.
I propose a 4th checkbox "Use FQDN". This will isolate username and passwords based on the complete FQDN vs. the Domain only portion IS does now. I propose the checkbox be unchecked for backwards compatibility but it will resolve the issue where IS gets confused and minimize having multiple entries for one domain.