Can I use a customer's information already stored as a "boilerplate" to create another separate entity? I have a customer with several LLC's but the same billing info.

I'm here to help you create another entity, glassmanhero. 

We're unable to copy an existing customer information to create another entity. We can use the details by manually entering them. QuickBooks also have the export and import options that can easily transfer reports and lists from one account to the other. 

We can take a screenshot of the companies information and then switch companies to copy it to the new one. Just click the gear icon and then Switch companies. For the export and import process, still from the gear icon and click Export data / Import data. 

You can always get back to me if you need anything else. Keep safe!