Ok, great.
I find this non-intuitive, but if you right-click the operator in the Console you can use the “Convert to LDAP Operator” option. I realize, it’s already an LDAP operator, and this function was intended to convert from a local operator to an LDAP operator, but you can also switch from one LDAP user to a different LDAP user.
( I only have one Domain for my test. You should probably create a new operator to test this migration in your two-domain scenario).

The ‘Convert to LDAP Operator’ dialog will pre-fill their existing account name for the search. You’ll need to remove part or all of their name to search for users in the right directory and hit the ‘Search’ button to refresh the user list.


It should be as simple as selecting the new account name and hitting the ‘Convert’ button.
The potential ‘gotcha’ is if you’re using LDAP Groups to assign BigFix Roles, you’ll need to ensure the new account is also in groups that are assigned to Roles in the server. My first try at this test worked, but my new test user was no longer allowed to log on because it was not in the LDAP groups that assigned my roles.