An employee was charged with failing to surrender insurance card while driving owner's vehicle.

Can the owner be charged later for not having insurance on the vehicle?

He did not give authorization for this vehicle to be driven.

Are you the boss now? 5 tickets and a promotion.... Yes you can be charged for up to 6 months. Not giving authorization is a possible defense to which the prosecutor will ask why you did not secure the keys and plates in a place unauthorized people who normally drive your vehicles could not get access to them.

can a charge be changed later?

The original charge against the driver doesn't need to be changed. The charge against the driver would be a new, separate charge. The police actually have up to three years to lay the charge since it falls under the Compulsory Automobile Insurance Act.

If the employee truly didn't have permission, that would be a defence. Keep in mind though the Courts/police are used to hearing that excuse from owners simply trying to avoid a charge. You're going to have to support the claim.

Edit: Above should have read "The charge against the owner would be a new, separate charge."