How does Claiming Accounts and Azure AD sync affect user directory and billing?

[Jan Radzikowski]

Hello,

I have 2 questions regarding Claiming accounts and Atlassian Access billing.
I am using Migration Test environment and i was able to migrate some of my projects from Server.
Users were migrated using Migration Assistant tool.
Projects were migrated using Site Import.

1 - Now I have to Claim accounts to be able to use Atlassian Access for Azure AD integration and AD user sync.
So i have an organization of 1000+ users (in terms of AD accounts). Out of it around 50 users using Jira Software / Service Management / Confluence. When i try to verify domain i get list of users accounts that i have to claim - these are external use of Trello or other Jira instances not connected with our environment at all.

I understand Claiming account will trigger mail notification only. But what is going to happen later after Azure Ad sync? Will these 2 directories merge or overwrite? What happens with accounts with same name but slightly different email address (ex. joe.doe@example.com vs jdoe@example.com)?

2 - billing - from documentation i understood that Atlassian access will be billed only against these 50 users who use Jira Tools and not all AD users?
AD users will only use Service Desk portal (to report support request) and i understand it is not type of access that is triggering any payment, am i right?