As a Xink admin, you can assign special signatures to users with access to shared mailboxes and to users that has access to more than one user mailbox.
A mailbox that's not primarily associated with a single user and is generally configured to allow logon access for multiple users.
A mailbox that's assigned to an individual user in your Exchange organization. It typically contains messages, calendar items, contacts, tasks, documents, and other important business data.
Method #1: When the email is used only a few times
You set the shared signatures as optional and assign it to the users(s) - Either individually or via group setting (rules).
Then the user can select the optional signature by right clicking the default (can also select in the Outlook menu).
Method #2: When the email is used many time
You select 'Do not change' which means that the user can select his own default/reply and the Xink client will not overwrite.
How to set 'Do not change' individually:
How to set 'Do not change' for groups via rules:
Now the the E-mail account settings are preserved when the Xink client updates: