Often the advisor will connect a custodian account to the parent or grantor of the gift for tracking purposes. They will want to be able to tell which account is the gift account vs other accounts in the report.
Advisors Assistant allows you to change the account number without affecting downloads. Downloads use the Control Number, so be sure not to change that field.
For example, you can change the account number of "7563498-1" to "7563498-1 Jimmy"