You may have to contact Virgin Mobile to add a new member to your account. You can add up to 5 members to your account and automatically get unlimited calling to each other.
Here's how to change your buddy numbers
MOBILE MY ACCOUNT
1. Head to my.vmobile.ca on a browser.
2. Hit My Buddies.
3. Scroll down and hit Edit.
4. Make your changes and Save.
MY ACCOUNT (on a computer)
1. Head to virginmobile.ca/myaccount and log in.
2. Click on My Service tab.
3. Click on My Plan and Features link.
4. Scroll down to Manage Feature Settings and click Change next to the My Buddies feature.
5. Make your changes, pick nicknames for your Buddies and Save
Hope that helps!