You should be able to add a new line of service to your account that already has the Jetpack. However you may have to pick a different plan for the phone if your current plan is exclusively for the Jetpack.
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.
ronin_7, we are excited to hear that you are looking to expand your services with us. You will be able to add a line to your existing account. Please review the steps here https://www.verizon.com/plans/add-a-line/. -Sylvia