We have recently setup a forest trust and configured GALSync between the 2 domains (working successfully).
Only annoying issue is that 1 domain uses Firstname-Lastname as the display name & the other uses Lastname-Firstname. So when a user is searching the Global Address List, they need to consider which domain the user is from & decide if they need to type the lastname or firstname.
If we changed the display name for the users in 1 of the domains so both domain display names are uniform, what type of issues would we potentially experience?
I am assuming the display name does not impact the mailbox or AD account. The only issue I can think of is users Autocomplete lists in Outlook (when you type first letter and the suggestions appear). These would no longer apply to those who's display name has changed. Would that mean that there could be a clash in the list and mail could fail to send to those users?