You can apply signatures for aliases in G Suite. It only requires one Xink license to update email signature for alias email addresses.
What is an email alias in G Suite?
Every user in a G Suite account has a primary address for signing in to their account and receiving mail. If a user wants another email address, you can create an email alias for them.
Why use an alias?
If email@example.com wants a sales address to post to the company website, you can create the alias firstname.lastname@example.org. Mail sent to either address then appears in Ann's Gmail inbox.
You can add up to 30 email aliases for each user. Users continue to sign in to their G Suite account with their primary address, not an email alias.
How to update email signature for aliases in Xink?
You apply the default email signature to all aliases when you select 'Apply to all aliases':